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GO-2026-5152

Traefik: SNICheck ignores wildcard TLSOptions mappings in github.com/traefik/traefik

Quick fix

GO-2026-5152 — github.com/traefik/traefik/v2: upgrade to the fixed version with the command below.

go get github.com/traefik/traefik/v2@v2.11.48

Details

The SNICheck middleware in Traefik ignores wildcard TLSOptions mappings, allowing an unauthenticated attacker to bypass mTLS requirements by using a domain-fronted request. This occurs because the middleware compares the TLS options name used during the handshake with a pre-computed value that may not account for wildcard matches correctly when certain configuration models are applied.

Are you affected?

Enter the version of the package you're using.

Affected packages

Go / github.com/traefik/traefik/v2
Introduced in: 0 Fixed in: 2.11.48
Fix go get github.com/traefik/traefik/v2@v2.11.48
Go / github.com/traefik/traefik/v3
Introduced in: 3.7.0 Fixed in: 3.7.3
Fix go get github.com/traefik/traefik/v3@v3.7.3

References