CVE-2026-4274 (GCVE-0-2026-4274)

Vulnerability from cvelistv5 – Published: 2026-03-26 10:43 – Updated: 2026-03-26 13:58
VLAI
Title
Insufficient authorization in shared channel membership sync grants team-level access instead of channel-level access
Summary
Mattermost versions 11.2.x <= 11.2.2, 10.11.x <= 10.11.10, 11.4.x <= 11.4.0, 11.3.x <= 11.3.1 fail to restrict team-level access when processing membership sync from a remote cluster, which allows a malicious remote cluster to grant a user access to an entire private team instead of only the shared channel via sending crafted membership sync messages that trigger team membership assignment. Mattermost Advisory ID: MMSA-2026-00574
Severity
5.4 (Medium)
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N
SSVC
Exploitation: none Automatable: no Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-03-26 13:58 UTC
CWE
  • CWE-863 - Incorrect Authorization
Assigner
Mattermost CNA under the mitre root
CNA scorecard B 80/100 over 128 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: 11.2.0 , ≤ 11.2.2 (semver)
Affected: 10.11.0 , ≤ 10.11.10 (semver)
Affected: 11.4.0 , ≤ 11.4.0 (semver)
Affected: 11.3.0 , ≤ 11.3.1 (semver)
Unaffected: 11.5.0
Unaffected: 11.2.3
Unaffected: 10.11.11
Unaffected: 11.4.1
Unaffected: 11.3.2
guessed Create a notification for this product.
Credits
daw10
Show details on NVD website
To clipboard 

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