23 Oct 2026 15:48:27 UTC
s2s-proxy accepts untrusted client certificates
cve-program · CVE-2026-96770 · Published
CVE-2026-96770
s2s-proxy accepts untrusted client certificates
CVSS 4.0 9.3 CRITICALCheck source for fixed versionsKEV status unknown
cve-program · CVE-2026-96770
PublishedAll 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.
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