# CVE-2026-65600: Traefik authentication bypass in ReplacePathRegex middleware

Source: https://junglewise.ai/threats/cve-2026-65600-traefik-authentication-bypass-in-replacepathregex-middleware  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-22. Updated: 2026-08-06  
License: CC BY 4.0 with a link back

CVE-2026-65600 · Severity: critical · CVSS 9.1 · Published 2026-07-22

A critical security flaw has been identified in Traefik, a popular tool used to route and manage web traffic. The vulnerability allows an unauthorized person to bypass security checks and access protected areas of a website or application by sending a specially crafted web request. This could lead to the exposure of sensitive administrative data or unauthorized changes to the system. Organizations using Traefik should update to the latest patched versions immediately to ensure their internal resources remain protected.

Technologies: [github.com/traefik/traefik (Go)](https://junglewise.ai/threats/technologies/github-com-traefik-traefik), [github.com/traefik/traefik/v2 (Go)](https://junglewise.ai/threats/technologies/github-com-traefik-traefik-v2), [github.com/traefik/traefik/v3 (Go)](https://junglewise.ai/threats/technologies/github-com-traefik-traefik-v3), [Traefik Labs Traefik Proxy](https://junglewise.ai/threats/technologies/traefik-proxy). Vendors: [Go](https://junglewise.ai/threats/vendors/go), [Traefik Labs](https://junglewise.ai/threats/vendors/traefik-labs).

## Quick answers

**Is CVE-2026-65600 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-65600 being exploited in the wild.

**How severe is CVE-2026-65600?** Critical severity, with a CVSS score of 9.1, published 22 July 2026.

**Which products and versions are affected?** github.com/traefik/traefik (Go) SEMVER:introduced=0, SEMVER:introduced=0,last_affected=1.7.34; github.com/traefik/traefik/v2 (Go) SEMVER:introduced=0,fixed=2.11.52; github.com/traefik/traefik/v3 (Go) SEMVER:introduced=0,fixed=3.6.23, SEMVER:introduced=0,fixed=3.6.23,introduced=3.7.0,fixed=3.7.7; Traefik Labs Traefik Proxy <= 3.6.22, >= 3.7.0, <= 3.7.6.

**Is there a fix for CVE-2026-65600?** Yes. github.com/traefik/traefik/v2 (Go): upgrade to 2.11.52 or later; github.com/traefik/traefik/v3 (Go): upgrade to 3.6.23, 3.7.7 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-65600 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-65600?** Check whether you run github.com/traefik/traefik (Go), github.com/traefik/traefik/v2 (Go), github.com/traefik/traefik/v3 (Go) or one of the others listed at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- github.com/traefik/traefik/v2 (Go): upgrade to 2.11.52 or later

  ```sh
  go get github.com/traefik/traefik/v2@v2.11.52
  ```

- github.com/traefik/traefik/v3 (Go): upgrade to 3.6.23, 3.7.7 or later

  ```sh
  go get github.com/traefik/traefik/v3@v3.7.7
  ```


## Technical details

A path traversal vulnerability exists in Traefik's ReplacePathRegex middleware when configured with regular expressions that capture user-controlled path segments without mandatory separators (e.g., '^/api(.*)'). The root cause is located in the ServeHTTP function of the replacepathregex package, which fails to perform post-replacement path normalization validation. An unauthenticated remote attacker can craft a request (e.g., '/api../admin') that, after regex substitution, produces an un-normalized path (e.g., '/../admin'). If the backend service normalizes this path, the attacker can bypass Traefik's authentication middleware to access protected resources. This issue has been addressed in versions 2.11.52, 3.6.23, and 3.7.7 by implementing a check that rejects requests where the replaced path does not match its normalized form.

## Affected products

- traefik traefik <= 1.7.34
- traefik traefik/v2 <= 2.11.51
- traefik traefik/v3 <= 3.6.22, >= 3.7.0, <= 3.7.6

## Identifiers

- CVE-2026-65600
- GHSA-cxjq-mrr5-89rv
- GO-2026-6208

## Timeline

- 2026-07-09: disclosed: Initial publication by rtribotte
- 2026-08-06: advisory: GitHub Advisory published

## References

- [https://api.github.com/users/C-h4ck-0](https://api.github.com/users/C-h4ck-0)
- [https://github.com/C-h4ck-0](https://github.com/C-h4ck-0)
- [https://api.github.com/users/C-h4ck-0/gists%7B/gist_id%7D](https://api.github.com/users/C-h4ck-0/gists%7B/gist_id%7D)
- [https://api.github.com/users/C-h4ck-0/repos](https://api.github.com/users/C-h4ck-0/repos)
- [https://avatars.githubusercontent.com/u/48152831?v=4](https://avatars.githubusercontent.com/u/48152831?v=4)
- [https://api.github.com/users/C-h4ck-0/events%7B/privacy%7D](https://api.github.com/users/C-h4ck-0/events%7B/privacy%7D)

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- [Traefik HTTP request smuggling via unrestricted protocol upgrade](https://junglewise.ai/threats/cve-2026-88008-traefik-http-request-smuggling-via-unrestricted-protocol-upgrade)