Authentication Bypass Using an Alternate Path or Channel Affecting github.com/traefik/traefik/v2/pkg/server package, versions <2.11.48
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-GITHUBCOMTRAEFIKTRAEFIKV2PKGSERVER-17748680
- published1 Jul 2026
- disclosed16 Jun 2026
- creditUnknown
Introduced: 16 Jun 2026
CVE-2026-48491 Â (opens in a new tab)How to fix?
Upgrade github.com/traefik/traefik/v2/pkg/server to version 2.11.48 or higher.
Overview
github.com/traefik/traefik/v2/pkg/server is a server package for traefik, a cloud native edge router.
Affected versions of this package are vulnerable to Authentication Bypass Using an Alternate Path or Channel in the SNICheck process. An attacker can gain unauthorized access to protected backends by completing a TLS handshake using a permissive SNI and then sending an HTTP Host header that targets a backend protected by stricter mutual TLS options. This is only exploitable if a wildcard router is configured with stricter TLS options and another permissive SNI is served on the same entrypoint, allowing the attacker to mismatch the SNI and HTTP Host header.
Workaround
This vulnerability can be mitigated by avoiding wildcard router TLSOptions for mTLS access control, enumerating exact protected hostnames instead of using wildcard Host rules, enforcing mTLS in the default TLS options, avoiding mixing permissive and mTLS-protected hosts on the same entrypoint, or blocking domain-fronted requests at another layer.