CVE-2026-8821
Last modified
CVE-2026-8821 is a high-severity vulnerability rated 7.1/10 on the CVSS scale. 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. EPSS estimates a 0.17% chance of exploitation in the next 30 days.
Description
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
Metrics
Weakness Enumeration
Affected Software
Source: CNA advisory (CVE.org). NVD analysis pending.
| Vendor | Product | Versions |
|---|---|---|
| Mattermost | Mattermost | >= 11.9.0, <= 11.9.0; >= 11.8.0, <= 11.8.4; >= 11.7.0, <= 11.7.7; >= 10.11.0, <= 10.11.22 |
References
Timeline
- Published
- Last Modified
- Status
- Awaiting Analysis
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