CVE-2026-96770 | BDVDB-2026-378477 Detail
Temporal Technologiess2s-proxy
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.
Impact#
An attacker who can reach the listener can connect as a trusted peer with a self-signed certificate and invoke allowed RPCs through the proxy's Temporal credentials. Impact depends on the RPC and namespace allowlists and the permissions granted to those credentials. A permissive deployment can expose workflow data or allow workflow changes and deletion. Data protected by a Payload Codec remains encrypted unless the attacker can also access the customer's Codec Server or encryption keys.
Weaknesses#
- CWE-296 Improper Following of a Certificate's Chain of Trust
References#
- https://github.com/temporalio/s2s-proxy/blob/v0.2.2/encryption/tls.go#L47-L62
- https://github.com/temporalio/s2s-proxy/commit/d100c2258dbc37d7df51298ea045315f36c7eb3b
- https://github.com/temporalio/s2s-proxy/pull/296
- https://github.com/temporalio/s2s-proxy/commit/f1dc6b9a3919d37e82545ab461cbe6bb62618d3c
- https://docs.temporal.io/production-deployment/data-encryption#codec-server-setup
Exploit#
No public exploit known
History#
- Version 1Record published in the CVE List.