Impact

There is a potential vulnerability in Traefik managing the TLS connections.

A router configured with a not well-formatted TLSOption is exposed with an empty TLSOption.

For instance, a route secured using an mTLS connection set with a wrong CA file is exposed without verifying the client certificates.

Patches

https://github.com/traefik/traefik/releases/tag/v2.9.6

Workarounds

Check the logs to detect the following error messages and fix your TLS options:

• Empty CA:

{"level":"error","msg":"invalid clientAuthType: RequireAndVerifyClientCert, CAFiles is required","routerName":"Router0@file"}

• Bad CA content (or bad path):

{"level":"error","msg":"invalid certificate(s) content","routerName":"Router0@file"}

• Unknown Client Auth Type:

{"level":"error","msg":"unknown client auth type \"FooClientAuthType\"","routerName":"Router0@file"}

• Invalid cipherSuites

{"level":"error","msg":"invalid CipherSuite: foobar","routerName":"Router0@file"}

• Invalid curvePreferences

{"level":"error","msg":"invalid CurveID in curvePreferences: foobar","routerName":"Router0@file"}

For more information

If you have any questions or comments about this advisory, please open an issue.