User Impersonation Affecting github.com/traefik/traefik/v3/pkg/middlewares/auth package, versions >=3.0.0-beta1 <3.6.11>=3.7.0-ea.1 <3.7.0-ea.3
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-GOLANG-GITHUBCOMTRAEFIKTRAEFIKV3PKGMIDDLEWARESAUTH-15812242
- published29 Mar 2026
- disclosed27 Mar 2026
- credit0xVijay
Introduced: 27 Mar 2026
CVE-2026-33433 Â (opens in a new tab)How to fix?
Upgrade github.com/traefik/traefik/v3/pkg/middlewares/auth to version 3.6.11, 3.7.0-ea.3 or higher.
Overview
Affected versions of this package are vulnerable to User Impersonation through the basicAuth and digestAuth middleware headerField handling in pkg/middlewares/auth/basic_auth.go and pkg/middlewares/auth/digest_auth.go. An attacker can impersonate an arbitrary user identity to backend services by sending a canonical headerField header value alongside valid credentials.
Notes
- The attacker must already authenticate successfully to Traefik with valid Basic or Digest credentials.
- The vulnerable behavior depends on backend applications trusting the configured
headerFieldheader for identity or authorization decisions.