CVE-2026-88011Traefik: ForwardAuth identity spoofing via dot-form header alias
Updated under an hour ago ()
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No exploitation reported and no EPSS estimate yet.
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Traefik is an open source HTTP reverse proxy and load balancer. Prior to 2.11.56, and from 3.0.0 until 3.7.12, a client-supplied dot-form header such as X.Authenticated.User survives ForwardAuth replacement and underscoreHeadersStrategy because Go treats it as distinct from X-Authenticated-User while normalization-prone CGI, WSGI, PHP, and NGINX backends collapse both names. A backend can consequently consume the client value instead of the identity Traefik asserted, allowing identity spoofing for any header managed by Traefik. The aliasHeadersStrategy protection is disabled by default and must be configured as delete or reject. The mitigation is available in 2.11.56 and 3.7.12.
- CVSS
- 5.3 MEDIUM (v4.0, CNA)CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N
- Weakness (CWE)
- CWE-290
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- GitHub_M
- NVD analysis
- Analyzed
- Record last updated
- Sep 15, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
traefik traefik traefik:traefik (from the name) | before 2.11.56; from 3.0.0, < 3.7.12 | CNA record |
traefik traefik traefik:traefik | before 2.11.56; from 3.0.0 before 3.7.12 | NVD |
References
- https://github.com/traefik/traefik/security/advisories/GHSA-rf44-j88r-hh8cx-refsource-confirm, patch, vendor-advisory
- https://github.com/traefik/traefik/pull/13720x-refsource-misc, issue-tracking, patch
- https://github.com/traefik/traefik/commit/0331801c72329e0eaeb850e53ccce87c57fbecf8x-refsource-misc, patch
- https://github.com/traefik/traefik/releases/tag/v2.11.56x-refsource-misc, release-notes
- https://github.com/traefik/traefik/releases/tag/v3.7.12x-refsource-misc, release-notes
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.