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. Temporal Cloud is not affected.

A writer role user in an attacker-controlled namespace could signal, delete, and reset workflows or activities in a victim namespace on the same cluster. Exploitation requires the attacker to know or guess specific victim workflow ID(s) and, for signal operations, signal names. This was due to a bug introduced in Temporal Server v1.29.0 which inadvertently allowed an attacker to control the namespace name value instead of using the server's own trusted name value within the batch activity code. The batch activity validated the namespace ID but did not cross-check the namespace name against the worker's bound namespace, allowing the per-namespace worker's privileged credentials to operate on an arbitrary namespace. Exploitation requires a server configuration where internal components have cross-namespace authorization, such as deployment of the internal-frontend service or equivalent TLS-based authorization for internal identities. This vulnerability also impacted Temporal Cloud when the attacker and victim namespaces were on the same cell, with the same preconditions as self-hosted clusters.

The Temporal api-go library prior to version 1.44.1 did not send `update response` information to Data Converter when the proxy package within the api-go module was used in a gRPC proxy prior to transmission. This resulted in information contained within the `update response` field not having Data Converter transformations (e.g. encryption) applied. This is an issue only when using the UpdateWorkflowExecution APIs (released on 13th January 2025) with a proxy leveraging the api-go library before version 1.44.1. Other data fields were correctly sent to Data Converter. This issue does not impact the Data Converter server. Data was encrypted in transit. Temporal Cloud services are not impacted.

Denial of Service in Temporal Server prior to version 1.20.5, 1.21.6, and 1.22.7 allows an authenticated user who has permissions to interact with workflows and has crafted an invalid UTF-8 string for submission to potentially cause a crashloop. If left unchecked, the task containing the invalid UTF-8 will become stuck in the queue, causing an increase in queue lag. Eventually, all processes handling these queues will become stuck and the system will run out of resources. The workflow ID of the failing task will be visible in the logs, and can be used to remove that workflow as a mitigation. Version 1.23 is not impacted. In this context, a user is an operator of Temporal Server.