Missing Authentication on Streaming gRPC Replication Endpoint

Summary

The frontend gRPC server's streaming interceptor chain did not include the authorization interceptor. When a ClaimMapper and Authorizer are configured, unary RPCs enforce authentication and authorization, but the streaming AdminService/StreamWorkflowReplicationMessages endpoint accepted requests without credentials. This endpoint is registered on the same port as WorkflowService and cannot be disabled independently. An attacker with network access to the frontend port could open the replication stream without authentication. Data exfiltration is possible, but  only when a configured replication target is correctly configured and the attacker has knowledge of the cluster configuration, as the history service validates cluster IDs and peer membership before returning replication data. The fix was applied per release line: it is present in 1.28.4, 1.29.6, 1.30.4, 1.31.2, and 1.32.0 and later releases on each line. Releases 1.31.0 and 1.31.1 do not contain the fix and are affected. Temporal Cloud is not affected.

Timeline

1. Apr 10, 2026, 9:06 PM UTCCVE published
2. Apr 13, 2026, 4:10 PM UTCCISA SSVC assessment

   Exploitation: none · Automatable: no · Technical impact: partial

3. Jul 8, 2026, 7:20 PM UTCRecord last updated

Affected versions

• temporal

  From 1.24.0 · fixed in 1.28.4; From 1.29.0 · fixed in 1.29.6; From 1.30.0 · fixed in 1.30.4; From 1.31.0 · fixed in 1.31.2

• go.temporal.io/serverGo

  fixed in 1.28.4; From 1.29.0-135.0 · fixed in 1.29.6; From 1.30.0-143.0 · fixed in 1.30.4

• go.temporal.io/serverGo

  fixed in 1.28.4

• go.temporal.io/serverGo

  From 1.29.0-135.0 · fixed in 1.29.6

• go.temporal.io/serverGo

  From 1.30.0-143.0 · fixed in 1.30.4

References 5