Authenticated identity spoofing via BasicAuth key collision
Published Aug 6, 2026 · Updated Aug 6, 2026
Improper authentication in Traefik Proxy 3.6.11 through 3.6.24 and 3.7.0 through 3.7.9 allows remote authenticated users to spoof identities. In pkg/middlewares/auth/basic_auth.go, checkPassword forms a singleflight key by concatenating password and secret without a delimiter, so concurrent distinct credential pairs share a successful result. Exploitation requires network access, a valid credential, its stored hash, and concurrent requests; headerField then forwards the unconfigured username as a trusted backend identity.
Summary
What happened
Improper authentication in Traefik Proxy 3.6.11 through 3.6.24 and 3.7.0 through 3.7.9 allows remote authenticated users to spoof identities. In pkg/middlewares/auth/basic_auth.go, checkPassword forms a singleflight key by concatenating password and secret without a delimiter, so concurrent distinct credential pairs share a successful result. Exploitation requires network access, a valid credential, its stored hash, and concurrent requests; headerField then forwards the unconfigured username as a trusted backend identity.
The record
- CVE
- CVE-2026-71326
- Published
- Aug 6, 2026
- Updated
- Aug 6, 2026
- Vendor
- Traefik Labs
- Product
- Traefik Proxy
- Classifications
- CWE-287, T1078
- Attack vector
- network
- Privileges
- authenticated
Timeline
How it unfolded
- Aug 6, 2026CVE publishedPublication date reported by the CVE source.
- Aug 6, 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=>= 3.6.11, < 3.6.25
- Affected versionversion=>= 3.7.0, < 3.7.10
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.
Public exploit references
- GHSA-6765-c87h-8mrf exploit clientproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
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Your stack
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