CVE-2026-88004

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    CVE-2026-88004

    Published: 10 Sept 2026Last Modified: 11 Sept 2026

    Summary: Traefik entrypoint header-name sanitization bypassed via request trailers

    Details: Traefik is an open source HTTP reverse proxy and load balancer. From 3.2.0 until 3.7.13, Traefik entrypoint defenses aliasHeadersStrategy, underscoreHeadersStrategy, and forwardedHeaders inspect req.Header but not req.Trailer, allowing an unauthenticated client to submit an aliasing or trusted header name in an HTTP/1.1 chunked trailer or an HTTP/2 trailer. When the retry or buffering middleware reads the body before the reverse proxy clones the request, the attacker-controlled trailer value reaches a backend that merges trailers into the header namespace, bypassing the documented delete or reject behavior and potentially spoofing identity or forwarded routing data. This issue is fixed in 3.7.13.

    References: https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/88xxx/CVE-2026-88004.json, https://github.com/traefik/traefik/commit/55bbda4f65e0f9c533c870983a767a7081126db7, https://github.com/traefik/traefik/pull/13822, https://github.com/traefik/traefik/releases/tag/v3.7.13, https://github.com/traefik/traefik/security/advisories/GHSA-v67p-phpq-fc8x, https://nvd.nist.gov/vuln/detail/CVE-2026-88004

    Affected packages

    Package

    Name:

    Purl:

    Affected ranges

    Type: GIT

    Events:

    Introduced- 25caa72c0972fcb829276ebf5a41ef0263fa4a6f
    Fixed -fc92cc118a0557a029c7019d5ee06665127b0f13

    Affected versions

    Common Vulnerability Scoring System

    Attack Vector
    Network
    Adjacent
    Local
    Physical
    Privileges Required
    None
    Low
    High
    User Interaction
    None
    Required
    Scope
    Unchanged
    Changed
    Confidentiality
    None
    Low
    High
    Integrity
    None
    Low
    High
    Availability
    None
    Low
    High
    CVE-2026-88004 | CVE-DB