CVE-2026-5199 Affecting temporal package, versions <1.6.2-r2
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-MINIMOSLATEST-TEMPORAL-15955152
- published9 Apr 2026
- disclosed1 Apr 2026
Introduced: 1 Apr 2026
NewCVE-2026-5199 (opens in a new tab)How to fix?
Upgrade Minimos:latest temporal to version 1.6.2-r2 or higher.
NVD Description
Note: Versions mentioned in the description apply only to the upstream temporal package and not the temporal package as distributed by Minimos.
See How to fix? for Minimos:latest relevant fixed versions and status.
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.
References
- https://www.cve.org/CVERecord?id=CVE-2026-5199
- https://github.com/advisories/GHSA-xpg8-3hhp-p7w8
- https://osv.dev/vulnerability/MINI-8v96-x5m6-v37q
- https://osv.dev/vulnerability/CVE-2026-5199
- https://github.com/temporalio/temporal/releases/tag/v1.29.5
- https://github.com/temporalio/temporal/releases/tag/v1.30.3