Cross Namespace Access via Batch Operation
Key facts
- Attack vector
- Network
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- High
- Attack requirements
- Present
- Impact type
- Security bypass
- Confidentiality · integrity · availability
- None · Low · Low
- Fix status
- Fixed
Attack profile from CVSS 4.0 · CNA. Fix status from CNA and GitHub. Impact type from CWE-639.
Summary
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.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Temporal Technologies, Inc. | temporal | 1.29.0 to before 1.29.5; 1.30.0 to before 1.30.3 | 1.29.5, 1.30.3 | Patch available | CNA |
| — | go.temporal.io/server (Go) | 1.30.0-143.0 to before 1.30.3 | 1.30.3 | Patch available | GHSA-xpg8-3hhp-p7w8 |
| — | go.temporal.io/server (Go) | before 1.29.5 | 1.29.5 | Patch available | GHSA-xpg8-3hhp-p7w8 |
- temporal VendorTemporal Technologies, Inc. Affected 1.29.0 to before 1.29.5; 1.30.0 to before 1.30.3 Fixed in 1.29.5, 1.30.3 Patch available CNA
- go.temporal.io/server (Go) Vendor— Affected 1.30.0-143.0 to before 1.30.3 Fixed in 1.30.3 Patch available GHSA-xpg8-3hhp-p7w8
- go.temporal.io/server (Go) Vendor— Affected before 1.29.5 Fixed in 1.29.5 Patch available GHSA-xpg8-3hhp-p7w8
Remediation
- Fix · CNA temporal (Temporal Technologies, Inc.) Fixed in 1.29.5, 1.30.3
- Fix · GHSA-xpg8-3hhp-p7w8 go.temporal.io/server (Go) Fixed in 1.30.3 Advisory →
- Fix · GHSA-xpg8-3hhp-p7w8 go.temporal.io/server (Go) Fixed in 1.29.5 Advisory →
Timeline
- 2026-10-02 Threatist record created from CVE-2026-5199
- 2026-10-03 Alias added: GHSA-xpg8-3hhp-p7w8
References
More Temporal Technologies, Inc. vulnerabilities
- TI-2026-63861 s2s-proxy accepts untrusted client certificates CVSS 4.0CRITICAL 9.3
- TI-2026-46800 temporalio/tchannel-go zero-chunk call fragment causes process termination CVSS 4.0HIGH 8.7
- TI-2026-46799 temporalio/tchannel-go malformed checksum type causes process termination CVSS 4.0HIGH 8.7
- TI-2026-46801 temporalio/ringpop-go fails to enforce configured label limits on inbound membership gossip CVSS 4.0HIGH 8.7
- TI-2026-13897 temporalio/sqlparser malformed MySQL version comments can cause a panic CVSS 4.0HIGH 8.7
- TI-2026-84119 Temporal Server k8s compute provider lets callers run host commands CVSS 4.0HIGH 8.7
Sources
- CVE-2026-5199 · CVE Program
- CVE-2026-5199 · NVD
- FIRST EPSS
- GHSA-xpg8-3hhp-p7w8 · GitHub Advisory Database · CC BY 4.0
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