CVE-2026-5199
Cross-Namespace Authorization Bypass in Temporal Server v
Publication date: 2026-04-01
Last updated on: 2026-04-01
Assigner: Temporal Technologies Inc.
Description
Description
CVSS Scores
EPSS Scores
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Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| temporal | temporal | 1.29.0 |
| temporal | temporal | 1.29.5 |
| temporal | temporal | 1.30.3 |
Helpful Resources
Exploitability
| CWE ID | Description |
|---|---|
| CWE-639 | The system's authorization functionality does not prevent one user from gaining access to another user's data or record by modifying the key value identifying the data. |
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?
This vulnerability allows a user with a writer role in an attacker-controlled namespace to signal, delete, and reset workflows or activities in a victim namespace on the same cluster.
The issue arises because the batch activity code incorrectly uses the namespace name value controlled by the attacker instead of the server's trusted namespace name. While the batch activity validates the namespace ID, it does not verify that the namespace name matches the worker's bound namespace, allowing privileged credentials to operate across namespaces.
Exploitation requires the attacker to know or guess specific victim workflow IDs and signal names, and the server must be configured to allow cross-namespace authorization among internal components.
How can this vulnerability impact me? :
An attacker exploiting this vulnerability could manipulate workflows or activities in other namespaces within the same cluster, potentially disrupting or interfering with legitimate operations.
This could lead to unauthorized signaling, deletion, or resetting of workflows, which may cause operational issues, data inconsistency, or denial of service within affected namespaces.
What immediate steps should I take to mitigate this vulnerability?
To mitigate the CVE-2026-5199 vulnerability, you should upgrade your Temporal Server to a version that includes the fix for this issue.
- Upgrade to Temporal version v1.29.5 or later, as this version includes proper validation of namespaces during batch workflow operations.
- Alternatively, upgrade to version v1.30.3 or later, which also addresses this vulnerability with enhanced namespace security checks.
These updates prevent attackers from exploiting insufficient namespace verification that could allow unauthorized control over workflows in other namespaces.
How does this vulnerability affect compliance with common standards and regulations (like GDPR, HIPAA)?:
The provided information does not specify how the CVE-2026-5199 vulnerability affects compliance with common standards and regulations such as GDPR or HIPAA.