CVE-2026-104355
Description
A flaw was found in Temporal Server. In a multi-cluster deployment, the server fails to verify whether inbound replication tasks apply only to global namespaces. An attacker controlling a connected peer cluster can exploit this vulnerability by sending replication updates that overwrite configuration settings for local namespaces. This unauthorized modification can alter namespace states and disrupt operations, leading to a Denial of Service (DoS) for workflows running in affected namespaces.
Statement
A moderate severity flaw was found in the Temporal Server component shipped in Red Hat Ansible Automation Orchestrator (automation-orchestrator-temporal-rhel9). In a multi-cluster Temporal deployment, the receiving cluster fails to verify that inbound namespace replication tasks apply only to global namespaces. An attacker who controls or compromises a registered peer cluster whose connection an administrator has enabled can send replication updates that overwrite the configuration of local namespaces, including state, owner, retention, archival settings, and active cluster assignment, without holding any credential on the receiving cluster. For example, marking a namespace Deprecated, making the peer its active cluster, or shortening its retention causes new workflow starts in that namespace to fail, resulting in denial of service. Deployments with no remote cluster registered with connection enabled are not exposed. Red Hat rates this flaw Moderate severity (CVSS 5.5, AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:L), lower than the upstream CVSS 4.0 score of 7.0 (Important), primarily because exploitation requires control of an administrator-registered peer cluster, a high-privilege precondition within the multi-cluster trust model. The fix for the affected Red Hat product is deferred because the impact is Moderate with a CVSS score below 7.0; the residual risk is limited to multi-cluster deployments that use replication with a compromised or attacker-controlled connected peer.
Mitigation
A workaround is available: administrators of multi-cluster Temporal deployments can eliminate the exposure by removing remote cluster registrations or disabling connections to remote clusters, since a cluster with no remote cluster registered with connection enabled is not vulnerable to this issue. Restricting network access so that only trusted, uncompromised peers can communicate with the cluster also reduces risk. Note that disabling remote cluster connections comes at the cost of cross-cluster replication functionality. Alternatively, upgrading Temporal Server to an upstream release that contains the fix addresses the issue.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 5.5 | N/A | N/A |
| Attack Vector | Network | N/A | N/A |
| Attack Complexity | Low | N/A | N/A |
| Privileges Required | High | N/A | N/A |
| User Interaction | None | N/A | N/A |
| Scope | Unchanged | N/A | N/A |
| Confidentiality | None | N/A | N/A |
| Integrity Impact | High | N/A | N/A |
| Availability Impact | Low | N/A | N/A |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:L
Understanding the Weakness (CWE)
Other
Technical Impact: Varies by Context
Allowing external control of system settings can disrupt service or cause an application to behave in unexpected, and potentially malicious ways.
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