CVE-2026-8821 (GCVE-0-2026-8821)

Vulnerability from cvelistv5 – Published: 2026-09-14 10:42 – Updated: 2026-09-14 11:19
VLAI
Title
Playbooks run owner channel membership permission bypass
Summary
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
Severity
7.1 (High)
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N
SSVC
Exploitation: none Automatable: no Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-09-14 11:03 UTC
CWE
Assigner
Mattermost CNA under the mitre root
CNA scorecard B 80/100 over 107 records in the last 180 days details
References
URL Tags
https://mattermost.com/security-updates vendor-advisory
Impacted products
Vendor Product Version CPE status
Mattermost Mattermost Affected: 11.9.0 , ≤ 11.9.0 (semver)
Affected: 11.8.0 , ≤ 11.8.4 (semver)
Affected: 11.7.0 , ≤ 11.7.7 (semver)
Affected: 10.11.0 , ≤ 10.11.22 (semver)
Unaffected: 11.10.0
Unaffected: 11.9.1
Unaffected: 11.8.5
Unaffected: 11.7.8
Unaffected: 10.11.23
guessed Create a notification for this product.
Credits
ilent0
Show details on NVD website
To clipboard 

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