Forwarded-header deletion via case-mismatched Connection tokens
Published Mar 5, 2026 · Updated Mar 5, 2026
Improper case handling in Traefik Proxy 2.11.9 through 2.11.37 and 3.1.3 through 3.6.8 allows remote attackers to delete forwarded headers. The XForwarded middleware's removeConnectionHeaders function compares protected Connection tokens case-sensitively before Go deletes named headers case-insensitively. The request must use HTTP/1.1 and a lowercase token; downstream authentication, authorization, routing, or scheme decisions are affected only when they rely on a removed header.
Summary
What happened
Improper case handling in Traefik Proxy 2.11.9 through 2.11.37 and 3.1.3 through 3.6.8 allows remote attackers to delete forwarded headers. The XForwarded middleware's removeConnectionHeaders function compares protected Connection tokens case-sensitively before Go deletes named headers case-insensitively. The request must use HTTP/1.1 and a lowercase token; downstream authentication, authorization, routing, or scheme decisions are affected only when they rely on a removed header.
The record
- CVE
- CVE-2026-29054
- Published
- Mar 5, 2026
- Updated
- Mar 5, 2026
- Vendor
- Traefik Labs
- Product
- Traefik Proxy
- Classifications
- CWE-178, T1565.002
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Mar 5, 2026CVE publishedPublication date reported by the CVE source.
- Mar 5, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
Compare your product and version with the public record. A matching version still requires validation against your environment.
Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=>= 2.11.9, < 2.11.38
- Affected versionversion=>= 3.1.3, < 3.6.9
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
- Attached deterministic integration 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
Check the software in your environment
Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.
Book a demo