Cross Namespace Access via Batch Operation

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Summary

CVECVE-2026-5199
StatePUBLISHED
AssignerTemporal
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-04-01 18:16:31 UTC
Updated2026-04-01 18:16:31 UTC
DescriptionA 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.

Risk And Classification

Primary CVSS: v4.0 2.3 LOW from [email protected]

CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:N/VI:L/VA:L/SC:N/SI:L/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:N/AU:Y/R:U/V:X/RE:M/U:X

Problem Types: CWE-639 | CWE-639 CWE-639 Authorization bypass through User-Controlled key

VersionSourceTypeScoreSeverityVector
4.0[email protected]Secondary2.3LOWCVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:N/VI:L/VA:L/SC:N/SI:L/SA:L/E:X/C...
4.0CNACVSS2.3LOWCVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:N/VI:L/VA:L/SC:N/SI:L/SA:L/S:N/A...

CVSS v4.0 Breakdown

Attack Vector
Network
Attack Complexity
High
Attack Requirements
Present
Privileges Required
Low
User Interaction
None
Confidentiality
None
Integrity
Low
Availability
Low
Sub Conf.
None
Sub Integrity
Low
Sub Availability
Low

CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:N/VI:L/VA:L/SC:N/SI:L/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:N/AU:Y/R:U/V:X/RE:M/U:X

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Temporal Technologies Inc. Temporal affected 1.29.0 1.29.5 semver Not specified
CNA Temporal Technologies Inc. Temporal affected 1.30.0 1.30.3 semver Not specified

References

ReferenceSourceLinkTags
github.com/temporalio/temporal/releases/tag/v1.29.5 [email protected] github.com
github.com/temporalio/temporal/releases/tag/v1.30.3 [email protected] github.com
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