CVE-2026-120091: Temporal Server arbitrary command execution via Kubernetes worker configuration

CVE-2026-120091 · Severity: info · Published 2026-11-02

Temporal Server, a distributed workflow engine, contains a flaw in its Worker Service that allows an authenticated user with read-only namespace access to execute arbitrary commands on the server host. The vulnerability exists in how the k8s compute provider builds its Kubernetes client from user-supplied configuration rather than operator configuration. An attacker can exploit this through a read-only API operation to gain control of the Worker Service process, compromising all cluster credentials and namespace data.

Technologies: Temporal Technologies Temporal Server. Vendors: Temporal Technologies.

Quick answers

Is CVE-2026-120091 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-120091 being exploited in the wild.
How severe is CVE-2026-120091?
Informational severity, published 2 November 2026.
Which products and versions are affected?
Temporal Technologies Temporal Server 1.31.0 through 1.31.2, 1.32.0 through 1.32.x (before 1.32 fix).
Is there a fix for CVE-2026-120091?
Yes: fixed in Temporal Server 1.31.3 and later 1.31 releases; 1.32.0 and later with default-deny allowlist enabled. Until then: Ensure the dynamic configuration setting workercontroller.compute_providers.enabled explicitly denies the k8s provider by default and does not include it in any namespace override unless required. Verify that authorization is properly configured with a real authorizer and claim mapper in place. Review custom authorizers to ensure they deny ValidateWorkerDeploymentVersionComputeConfig access to callers without namespace write permissions. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-120091 attacked?
It is attacked over the network, in a hosted service.
Am I affected by CVE-2026-120091?
Check whether you run Temporal Technologies Temporal Server at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

  • Fixed in: Temporal Server 1.31.3 and later 1.31 releases; 1.32.0 and later with default-deny allowlist enabled

Ensure the dynamic configuration setting workercontroller.compute_providers.enabled explicitly denies the k8s provider by default and does not include it in any namespace override unless required. Verify that authorization is properly configured with a real authorizer and claim mapper in place. Review custom authorizers to ensure they deny ValidateWorkerDeploymentVersionComputeConfig access to callers without namespace write permissions.

Technical details

The Worker Controller Instance module in Temporal Server registers a k8s compute provider that constructs a Kubernetes client from caller-supplied request data rather than operator-controlled configuration. An authenticated attacker with read-only namespace role can reach the vulnerable code path via ValidateWorkerDeploymentVersionComputeConfig without needing namespace write access or an existing worker deployment. Exploitation occurs during configuration validation and grants command execution as the Worker Service process account, which holds cluster-wide credentials and TLS material.

Affected products

  • Temporal Technologies Temporal Server 1.31.0 through 1.31.2, 1.32.0 through 1.32.x (before 1.32 fix)

Timeline

  • 2026-11-02: disclosed

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