GHSA-6jwx-7vp4-9847 — v3
HIGHGHSA-6jwx-7vp4-9847 is a high-severity (CVSS 8.2) CWE-706 vulnerability in github.com/traefik/traefik/v3. A fix is available for github.com/traefik/traefik/v3 — see the affected versions and patch details below.
Traefik has an StripPrefixRegex Middleware Authorization Bypass via Path/RawPath Desync
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for GHSA-6jwx-7vp4-9847.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
GHSA-6jwx-7vp4-9847 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 376,715 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
github.com/traefik/traefik/v3🐹github.com/traefik/traefik/v3🐹github.com/traefik/traefik/v2🐹github.com/traefik/traefikReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
Summary
There is a high severity authentication bypass vulnerability in Traefik's StripPrefixRegex middleware when used in combination with ForwardAuth, BasicAuth, or DigestAuth.
The middleware matches the regex against the decoded URL path but uses the resulting byte length to slice the percent-encoded raw path. When a dot (or multiple dots) appears in the prefix portion of the URL, the raw path after stripping becomes a dot-segment (e.g. /./admin/secret).
ForwardAuth receives this dot-segment path in X-Forwarded-Uri, which does not match the protected path patterns and therefore allows the request through. The backend then normalizes the dot-segment to the real path per RFC 3986 and serves the protected content
An unauthenticated attacker can exploit this against any backend that performs dot-segment normalization.
Patches
- https://github.com/traefik/traefik/releases/tag/v2.11.43
- https://github.com/traefik/traefik/releases/tag/v3.6.14
- https://github.com/traefik/traefik/releases/tag/v3.7.0-rc.2
For more information
If there are any questions or comments about this advisory, please open an issue.
<details> <summary>Original Description</summary>Summary
StripPrefixRegex uses the byte length of a decoded Path match to slice the encoded RawPath. When percent-encoded characters are in the prefix region, this produces a wrong RawPath. ForwardAuth then receives this wrong path in X-Forwarded-Uri, sees a path that doesn't match its protection rules, and approves the request. The backend serves protected content.
Details
pkg/middlewares/stripprefixregex/strip_prefix_regex.go, line 62:
req.URL.RawPath = ensureLeadingSlash(req.URL.RawPath[len(prefix):])
prefix comes from matching the regex against the decoded req.URL.Path (line 51). len(prefix) is then used to index into the encoded req.URL.RawPath. These lengths don't match when percent-encoding is present.
Example with regex ^/api:
- GET /api%20/admin/secret
- Decoded Path: /api /admin/secret -> prefix = /api (4 bytes)
- Encoded RawPath: /api%20/admin/secret -> same region is 6 bytes
- RawPath[4:] = %20/admin/secret -> after ensureLeadingSlash -> /%20/admin/secret
- ForwardAuth sees X-Forwarded-Uri: /%20/admin/secret -> not /admin/* -> allows it
- Backend serves the protected admin content
PoC
Requires Docker and Docker Compose. I have a setup that runs Traefik v3.6.11 with StripPrefixRegex + ForwardAuth + a backend. It sends a normal request (blocked, 403) and an encoded request (bypasses auth, 200, returns protected data). Can share the files here if useful.
Impact
Auth bypass. Any path protected by ForwardAuth, BasicAuth, or DigestAuth can be accessed without credentials when StripPrefixRegex is in the same middleware chain. The attacker only needs to add a percent-encoded character to the prefix portion of the URL.
Updated PoC (reporter follow-up)
After further testing, the confirmed working exploit uses %2e (percent-encoded dot) rather than %20. Dot-segment normalization (/./ -> /) is RFC 3986 standard behavior handled automatically by Express.js, Go's http.ServeMux, Spring Boot, and others — no custom configuration needed.
Chain:
GET /api%2e/admin/secret
-> StripPrefixRegex strips /api -> RawPath becomes /./admin/secret
-> ForwardAuth sees /./admin/secret -> does not match /admin/ -> allows
-> Express normalizes /./admin/secret -> /admin/secret -> serves protected content
Results (Traefik v3.6, unmodified Express.js express.static):
GET /api/admin/secret -> 403 (blocked)
GET /api%2e/admin/secret -> 200 (bypass — served protected content)
GET /api%20/admin/secret -> 404 (space not normalized by backend)
Auth server logs:
X-Forwarded-Uri: '/admin/secret' -> DENIED
X-Forwarded-Uri: '/./admin/secret' -> ALLOWED
Reproduction:
docker compose up -d --build --wait
curl http://localhost:8080/api/admin/secret # -> 403
curl --path-as-is "http://localhost:8080/api%2e/admin/secret" # -> 200
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/traefik/traefik/v3 | ≥ 3.7.0-ea.1&&< 3.7.0-rc.2 | 3.7.0-rc.2go get github.com/traefik/traefik/v3@v3.7.0-rc.2 |
| 🐹Go | github.com/traefik/traefik/v3 | ≥ 3.0.0-beta1&&< 3.6.14 | 3.6.14go get github.com/traefik/traefik/v3@v3.6.14 |
| 🐹Go | github.com/traefik/traefik/v2 | all versions | 2.11.43go get github.com/traefik/traefik/v2@v2.11.43 |
| 🐹Go | github.com/traefik/traefik | all versions | No fix |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/traefik/traefik/v3, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/traefik/traefik/v3 to 3.7.0-rc.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-6jwx-7vp4-9847 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-6jwx-7vp4-9847 can be triaged on real exposure rather than presence alone.
Tailored to GHSA-6jwx-7vp4-9847. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat OpenShift Dev Spaces 3.28 | devspaces/traefik-rhel9:1779786779 | RHSA-2026:21772 |
Frequently Asked Questions
Is GHSA-6jwx-7vp4-9847 in your dependencies?
O3 Security finds GHSA-6jwx-7vp4-9847 across Go dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.