๐Ÿ” CVE Alert

CVE-2026-96770

UNKNOWN 0.0

s2s-proxy accepts untrusted client certificates

CVSS Score
0.0
EPSS Score
0.0%
EPSS Percentile
0th

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.

CWE CWE-296
Vendor temporal technologies, inc.
Product s2s-proxy
Published Sep 23, 2026
Last Updated Sep 23, 2026
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Affected Versions

Temporal Technologies, Inc. / s2s-proxy
0.0.1-alpha โ‰ค 0.2.2

References

NVD โ†— CVE.org โ†— EPSS Data โ†—
github.com: https://github.com/temporalio/s2s-proxy/blob/v0.2.2/encryption/tls.go#L47-L62 github.com: https://github.com/temporalio/s2s-proxy/commit/d100c2258dbc37d7df51298ea045315f36c7eb3b github.com: https://github.com/temporalio/s2s-proxy/pull/296 github.com: https://github.com/temporalio/s2s-proxy/commit/f1dc6b9a3919d37e82545ab461cbe6bb62618d3c docs.temporal.io: https://docs.temporal.io/production-deployment/data-encryption#codec-server-setup

Credits

Praetorian, who reported this issue responsibly to Temporal Technologies