CVE-2026-40912
Traefik: StripPrefixRegex auth bypass via Path/RawPath desync
- Published
- Updated
- Reserved
- Assigned by
- GitHub_M
Description
Traefik is an HTTP reverse proxy and load balancer. Prior to versions 2.11.43, 3.6.14, and 3.7.0-rc.2, 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. This issue has been patched in versions 2.11.43, 3.6.14, and 3.7.0-rc.2.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| GitHub_MCNA (assigner) | 4.0 | High7.8 | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:L/SA:N |
| redhat-SADPADP (enrichment) | 3.1 | High8.6 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N |
| NVDNVD · Modified | 4.0 | High7.8 | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X |
- EPSS (exploitation in 30 days)
- 0.77% · top 44% of all CVEs (6 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: yes · Technical impact: partial
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.8.
Weakness
Affected products
Affected packages
From reviewed advisories of the GitHub Advisory Database.
- Gogithub.com/traefik/traefikGHSA-6jwx-7vp4-9847 (opens in a new tab)
- Gogithub.com/traefik/traefik/v2GHSA-6jwx-7vp4-9847 (opens in a new tab)
- Gogithub.com/traefik/traefik/v3GHSA-6jwx-7vp4-9847 (opens in a new tab)
References (8)
- https://github.com/traefik/traefik/security/advisories/GHSA-6jwx-7vp4-9847 (opens in a new tab)x_refsource_CONFIRM
- https://github.com/traefik/traefik/releases/tag/v2.11.43 (opens in a new tab)x_refsource_MISC
- https://github.com/traefik/traefik/releases/tag/v3.6.14 (opens in a new tab)x_refsource_MISC
- https://github.com/traefik/traefik/releases/tag/v3.7.0-rc.2 (opens in a new tab)x_refsource_MISC
- https://access.redhat.com/security/cve/CVE-2026-40912 (opens in a new tab)vdb-entryx_refsource_REDHAT
- RHBZ#2464229 (opens in a new tab)issue-trackingx_refsource_REDHAT
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-40912.json (opens in a new tab)x_sadp-csaf-vex
- https://access.redhat.com/errata/RHSA-2026:21772 (opens in a new tab)vendor-advisoryx_refsource_REDHAT
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisory GHSA-6jwx-7vp4-9847 (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://trackcve.app/cve/CVE-2026-40912)Record last updated .