Quick answers
- Is CVE-2026-9812 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-9812 being exploited in the wild.
- How severe is CVE-2026-9812?
- Medium severity, with a CVSS score of 6.5, published 14 September 2026.
- Which products and versions are affected?
- Mattermost Playbooks 11.9.x <= 11.9.0, 11.8.x <= 11.8.4, 11.7.x <= 11.7.7, 10.11.x <= 10.11.22.
- Is there a fix for CVE-2026-9812?
- A patch was published on 2026-09-14: Patches available: 11.9.1+, 11.8.5+, 11.7.8+, 10.11.23+ Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is CVE-2026-9812 attacked?
- It is attacked over the network, in a software library.
- Am I affected by CVE-2026-9812?
- Check whether you run Mattermost Playbooks at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
Technical details
This is an authorization/validation bypass vulnerability in the Mattermost Playbooks plugin's property field management API. The vulnerable component fails to verify that a property field belongs to the specified run before processing update requests. The attack requires network access to the REST API and valid authentication credentials with run property-management access. An attacker can trigger a denial-of-service condition by referencing a property field from an unrelated run, crashing the Playbooks plugin. Patches are available in versions 11.9.1+, 11.8.5+, 11.7.8+, and 10.11.23+.
Affected products
- Mattermost Playbooks 11.9.x <= 11.9.0, 11.8.x <= 11.8.4, 11.7.x <= 11.7.7, 10.11.x <= 10.11.22
Timeline
- 2026-09-14: disclosed
- 2026-09-14: patched: Patches available: 11.9.1+, 11.8.5+, 11.7.8+, 10.11.23+