Security-header removal via crafted Connection tokens
Published Aug 3, 2021 · Updated Aug 3, 2024
Header handling in Traefik Proxy 1.7.30 and earlier and 2.x before 2.4.13 allows remote attackers to drop request headers. A client-nominated Connection token survives until after Headers or ForwardAuth middleware runs, so later hop-by-hop cleanup deletes the header that middleware set. Exploitation requires a matching middleware chain and a backend that trusts the missing header, enabling a deployment-specific security-control bypass.
Summary
What happened
Header handling in Traefik Proxy 1.7.30 and earlier and 2.x before 2.4.13 allows remote attackers to drop request headers. A client-nominated Connection token survives until after Headers or ForwardAuth middleware runs, so later hop-by-hop cleanup deletes the header that middleware set. Exploitation requires a matching middleware chain and a backend that trusts the missing header, enabling a deployment-specific security-control bypass.
The record
- CVE
- CVE-2021-32813
- Published
- Aug 3, 2021
- Updated
- Aug 3, 2024
- Vendor
- Traefik Labs
- Product
- Traefik Proxy
- Classifications
- CWE-913, T1190
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Aug 3, 2021CVE publishedPublication date reported by the CVE source.
- Aug 3, 2024Record 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=<= 1.7.30
- Affected versionversion=< 2.4.13
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
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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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