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[ CVE-2026-96770 · Published 23 Sep 2026 ]

Vulnerability in Temporal Technologies, Inc. s2s-proxy

CVSS 9.3 EPSS <1%No fix listed yet

[ Why it matters ]Priority signals

  • Critical severity: CVSS 9.3

[ Description ]Official 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.

[ Fixes ]Fixes and patches

No fix or interim patch is linked from our sources yet. Check the vendor references below and limit exposure of affected systems until a fix is available.

[ References ]References