Vulnerability Description
All published s2s-proxy versions through 0.2.2 are affected. In versions 0.1.16 through 0.2.2, TLS server listeners use Go's RequireAnyClientCert mode when skipCAVerification is false. This mode checks that the client holds the certificate's private key but does not verify the certificate against the configured CA. An attacker can therefore use a self-signed certificate and key to establish a TLS and yamux connection, then invoke RPCs allowed by the proxy's configuration and Temporal credentials. No certificate or private key trusted by the deployment, and no Temporal credential, is required.
Related Weaknesses (CWE)
References
- https://docs.temporal.io/production-deployment/data-encryption#codec-server-setu
- https://github.com/temporalio/s2s-proxy/blob/v0.2.2/encryption/tls.go#L47-L62
- https://github.com/temporalio/s2s-proxy/commit/d100c2258dbc37d7df51298ea045315f3
- https://github.com/temporalio/s2s-proxy/commit/f1dc6b9a3919d37e82545ab461cbe6bb6
- https://github.com/temporalio/s2s-proxy/pull/296
FAQ
What is CVE-2026-96770?
CVE-2026-96770 is a documented vulnerability. All published s2s-proxy versions through 0.2.2 are affected. In versions 0.1.16 through 0.2.2, TLS server listeners use Go's RequireAnyClientCert mode when skipCAVerification is false. This mode check...
How severe is CVE-2026-96770?
CVSS scoring is not yet available for CVE-2026-96770. Check NVD for updates.
Is there a patch for CVE-2026-96770?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.