CVE-2026-5199Low▾ SunlitTemporal Server: attacker-controlled namespace could signal, delete, and reset workflows or activities in a victim namespace on the same cluster
▾ Sunlit zone — Low / medium · no exploitation signal
impact 13.8 · likelihood 0 · exploitation 0
Need a working PoC? Pro members can cast a request and our team develops one — it lands right here.
Exploit-prediction probability, daily snapshots since Jul 21.
Disclosure to exploitation, from the record and what we observed since indexing it.
Disclosed via OSV
Last analysed / modified upstream
0.2%
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.
go.temporal.io/server >= 1.30.0-143.0, < 1.30.3go.temporal.io/server < 1.29.5Upgrade to a patched release:
go.temporal.io/server 1.30.3go.temporal.io/server 1.29.5Connected by shared product, vendor, weakness, or advisory.
CVE-2026-89139High· 8.7Temporal Server compiles a Worker Controller Instance module into its Worker Service, and that module registers a compute provider named subprocess whose function is to launch a worker by running a command on the machine hosting the Work…
CVE-2026-87858High· 7.2Temporal Server decided whether a Workflow completion callback was internal by reading a caller-supplied HTTP header
CVE-2026-16652High· 7.1Temporal Server did not bound the work performed while searching for a Schedule's next action time