A flaw in Temporal Server caused an attacker who has writer privileges in one namespace to supply a forged namespace name to a batch operation. The batch activity validated only the namespace ID, not the trusted server‑derived name, allowing it to act on any namespace in the cluster. With this access, the malicious user can signal, delete, or reset any workflow or activity that belongs to another namespace, giving them the ability to disrupt services, tamper with data, or deny service to affected users.

Temporal Technologies’ Temporal Server software, specifically versions starting at v1.29.0 and continuing through the unpatched releases that precede the patch releases v1.29.5 and v1.30.3. Both self‑hosted clusters and Temporal Cloud installations where the attacker and victim namespaces share the same cell are susceptible.

The CVSS score of 2.3 rates this as a low‑severity issue, and no EPSS data or KEV listing is available. Exploitation requires the attacker to know or guess specific workflow identifiers and, for signal operations, the signal names, in addition to having an environment that enables internal cross‑namespace authorization such as an internal‑frontend service or TLS‑based internal identities. Because these conditions must be met and the vulnerability affects only privileged namespace users, the likelihood of widespread exploitation is modest, though it remains a serious concern for configurations that share a cluster across namespaces.