CVE-2026-89140
Description
A flaw was found in Temporal Server. Internal completion callbacks are not properly restricted to the namespace that created them, allowing a cross-namespace authorization bypass. An authenticated attacker with write permissions in one namespace can submit forged internal callbacks to manipulate schedule states in another namespace. This flaw enables an attacker to tamper with workflow scheduling, inject unauthorized data into subsequent tasks, or cause a denial of service by pausing scheduled workflows.
Statement
This vulnerability is classified as Moderate severity because exploitation requires an authenticated caller with valid write access in a namespace as well as exact knowledge of the target schedule identifier and action timing. Default deployments in Red Hat Ansible Automation Platform do not enable Scheduler V2, limiting practical exposure to instances where this capability was manually turned on. Although forged callbacks can alter schedule execution states or corrupt parameters passed to subsequent tasks, the issue cannot be leveraged to read confidential workflow payloads or execution history.
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 | 5.9 | N/A | N/A |
| Attack Vector | Network | N/A | N/A |
| Attack Complexity | High | N/A | N/A |
| Privileges Required | Low | 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:H/PR:L/UI:N/S:U/C:N/I:H/A:L
Understanding the Weakness (CWE)
Access Control
Technical Impact: Bypass Protection Mechanism
Access control checks for specific user data or functionality can be bypassed.
Access Control
Technical Impact: Gain Privileges or Assume Identity
Horizontal escalation of privilege is possible (one user can view/modify information of another user).
Access Control
Technical Impact: Gain Privileges or Assume Identity
Vertical escalation of privilege is possible if the user-controlled key is actually a flag that indicates administrator status, allowing the attacker to gain administrative access.
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