CVE-2026-8821 Affecting mattermost-10.11 package, versions <10.11.23-r0
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-MINIMOSLATEST-MATTERMOST1011-20654949
- published9 Oct 2026
- disclosed14 Sept 2026
Introduced: 14 Sep 2026
CVE-2026-8821 (opens in a new tab)How to fix?
Upgrade Minimos:latest mattermost-10.11 to version 10.11.23-r0 or higher.
NVD Description
Note: Versions mentioned in the description apply only to the upstream mattermost-10.11 package and not the mattermost-10.11 package as distributed by Minimos.
See How to fix? for Minimos:latest relevant fixed versions and status.
Mattermost versions 11.9.x <= 11.9.0, 11.8.x <= 11.8.4, 11.7.x <= 11.7.7, 10.11.x <= 10.11.22 fail to validate channel member-management permission during playbook run creation, allowing an authenticated channel member to add an arbitrary user to a restricted channel via the run owner field.. Mattermost Advisory ID: MMSA-2026-00677