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CVE-2026-88011

Traefik: ForwardAuth identity spoofing via dot-form header alias PUBLISHED

Description (CNA)

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.

Affected (CNA)

Vendor / productVersions
traefik / traefikaffected < 2.11.56; affected >= 3.0.0, < 3.7.12

CWE

CWE-290

References

ADP enrichment

CISA-ADP

No English description supplied.

No references supplied.