Detect CVE-2025-31125: Vite Dev Server Improper Access Control in Elastic Security
Detects exploitation of CVE-2025-31125, an improper access control vulnerability in Vite (Vitejs) dev server. The vulnerability allows unauthorized access to sensitive files outside the intended serve root, classified under CWE-200 (Information Exposure) and CWE-284 (Improper Access Control). This vulnerability is listed in CISA KEV, indicating active exploitation in the wild.
MITRE ATT&CK
- Tactic
- Initial Access Discovery Collection
Elastic Detection Query
sequence by source.ip with maxspan=5m
[network where event.category == "network" and
url.path : ("*/@fs/*", "*/__vite_ping*", "*/__vite_hmr*") and
(
url.path : ("*../*", "*%2e%2e*", "*/.env*", "*/etc/passwd*", "*/etc/shadow*", "*/proc/self/*") or
url.path : ("*/@fs/[A-Z]:*", "*/@fs//etc*", "*/@fs//home*", "*/@fs//root*")
)
]
[network where event.category == "network" and
http.response.status_code == 200 and
url.path : ("*/@fs/*")
]EQL sequence detection identifying successful file exfiltration attempts via Vite /@fs/ endpoint — first a suspicious path request, then a 200 OK response indicating successful unauthorized file access.
Data Sources
Required Tables
False Positives & Tuning
- Legitimate Vite module federation accessing cross-origin packages via /@fs/
- Workspace package resolution in monorepo environments with allowed path configurations
- Security researchers performing authorized vulnerability assessments
- Development tooling that programmatically accesses Vite dev server endpoints
Other platforms for CVE-2025-31125
Testing Methodology
Validate this detection against 3 adversary techniques from Atomic Red Team. Each test below lists the behaviour to exercise and the telemetry you should expect to see. Executable commands and cleanup steps are available with Pro.
- Test 1Vite /@fs/ Path Traversal to Read /etc/passwd
Expected signal: HTTP GET request to /@fs/etc/passwd and variants logged in web server access logs; Node.js process accessing /etc/passwd on the file system; network connection from test host to port 5173
- Test 2Vite Dev Server Environment File Extraction
Expected signal: HTTP requests to /@fs/ with absolute paths to .env files; file system read events on .env and config files; response body containing environment variable content if successful
- Test 3Automated CVE-2025-31125 Exploitation Scan
Expected signal: Rapid sequential HTTP GET requests to /@fs/ endpoint with multiple sensitive path targets; consistent source IP across all requests; mix of 200 and 403 response codes; elevated request rate to Vite dev server port
Unlock Pro Content
Get the full detection package for CVE-2025-31125 including response playbook, investigation guide, and atomic red team tests.