Authentication bypass via unfiltered X-Forwarded-Prefix forwarding
Published Apr 30, 2026 · Updated Apr 30, 2026
Authentication bypass in affected Traefik Proxy releases allows remote attackers to reach protected routes via a spoofed forwarded header. ForwardAuth copies incoming headers into the authentication subrequest but neither removes nor rebuilds X-Forwarded-Prefix when trustForwardHeader is false. Exploitation requires a trusted upstream proxy and an auth service that bases authorization or routing on the prefix; success exposes protected backend routes.
Summary
What happened
Authentication bypass in affected Traefik Proxy releases allows remote attackers to reach protected routes via a spoofed forwarded header. ForwardAuth copies incoming headers into the authentication subrequest but neither removes nor rebuilds X-Forwarded-Prefix when trustForwardHeader is false. Exploitation requires a trusted upstream proxy and an auth service that bases authorization or routing on the prefix; success exposes protected backend routes.
The record
- CVE
- CVE-2026-35051
- Published
- Apr 30, 2026
- Updated
- Apr 30, 2026
- Vendor
- Traefik Labs
- Product
- Traefik Proxy
- Classifications
- CWE-345, T1190
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Apr 30, 2026CVE publishedPublication date reported by the CVE source.
- Apr 30, 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=< 2.11.43
- Affected versionversion=>= 3.0.0-beta1, < 3.6.14
- Affected versionversion=>= 3.7.0-ea.1, < 3.7.0-rc.2
What conditions does exploitation require?
What is affected?
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
- GHSA-6384-m2mw-rf54 Docker proof of conceptproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
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