Authenticated identity spoofing via dot-form header alias
Published Sep 10, 2026 · Updated Sep 10, 2026
Authentication bypass in Traefik Proxy 2.11.55 and earlier and 3.0.0 through 3.7.11 allows remote authenticated users to spoof identities. ForwardAuth replaces only the canonical identity-header key, leaving a client-supplied dot-form alias that normalization-prone backends collapse into the same variable and can consume last. Exploitation requires a permitted lower-privilege request, a managed identity header, and an affected backend; success grants the backend identity or role selected by the attacker.
Summary
What happened
Authentication bypass in Traefik Proxy 2.11.55 and earlier and 3.0.0 through 3.7.11 allows remote authenticated users to spoof identities. ForwardAuth replaces only the canonical identity-header key, leaving a client-supplied dot-form alias that normalization-prone backends collapse into the same variable and can consume last. Exploitation requires a permitted lower-privilege request, a managed identity header, and an affected backend; success grants the backend identity or role selected by the attacker.
The record
- CVE
- CVE-2026-88011
- Published
- Sep 10, 2026
- Updated
- Sep 10, 2026
- Vendor
- Traefik Labs
- Product
- Traefik Proxy
- Classifications
- CWE-290, T1190
- Attack vector
- network
- Privileges
- authenticated
Timeline
How it unfolded
- Sep 10, 2026CVE publishedPublication date reported by the CVE source.
- Sep 10, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=< 2.11.56
- Affected versionversion=>= 3.0.0, < 3.7.12
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- Traefik dot-form ForwardAuth proof of conceptfunctional · demonstrated
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Technologies
Your stack
See the directory against your own environment.
Your stack
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