Identity spoofing via unsanitized request trailers
Published Sep 10, 2026 · Updated Sep 10, 2026
Header sanitization bypass in Traefik Proxy 3.2.0 through 3.7.12 allows remote attackers to spoof trusted backend headers via trailers. Entrypoint defenses inspect req.Header but not req.Trailer, so buffering or retry body reads can move attacker-controlled trailer values into a backend's merged header namespace. Exploitation requires a route using buffering or retry and a backend that merges trailers with headers; the result can spoof identity or forwarded routing data.
Summary
What happened
Header sanitization bypass in Traefik Proxy 3.2.0 through 3.7.12 allows remote attackers to spoof trusted backend headers via trailers. Entrypoint defenses inspect req.Header but not req.Trailer, so buffering or retry body reads can move attacker-controlled trailer values into a backend's merged header namespace. Exploitation requires a route using buffering or retry and a backend that merges trailers with headers; the result can spoof identity or forwarded routing data.
The record
- CVE
- CVE-2026-88004
- Published
- Sep 10, 2026
- Updated
- Sep 10, 2026
- Vendor
- Traefik Labs
- Product
- Traefik Proxy
- Classifications
- T1190
- Attack vector
- network
- Privileges
- unauthenticated
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=>= 3.2.0, < 3.7.13
What conditions does exploitation require?
What is affected?
Published CVSS scores
No CVSS assessment is available in this record.
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Attacks
What attackers are doing with it
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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