CVE-2026-6342

EUVD-2026-30745
Mattermost Plugins versions <=11.5 11.1.5 10.13.11 11.3.4.0 fail to appropriately check for valid namespaces which allows plugin users to create subscriptions to groups that were not whitelisted via creating groups that share the same prefix as a whitelisted group. Mattermost Advisory ID: MMSA-2026-00601
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
MattermostCNA
4.3 MEDIUM
NETWORK
LOW
LOW
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
Base Score
CVSS 3.x
EPSS Score
Percentile: 4%
Affected Products (NVD)
VendorProductVersion
mattermostmattermost_server
10.13.0 ≤
𝑥
≤ 10.13.11
mattermostmattermost_server
11.1.0 ≤
𝑥
≤ 11.1.5
mattermostmattermost_server
11.3.0 ≤
𝑥
≤ 11.3.4
𝑥
= Vulnerable software versions
Early Detection
Affected products identified ahead of NVD analysis through intelligence sources.
VendorProductVersionSource
mattermostmattermost
𝑥
≤ 11.1.5
CNA
mattermostmattermost
𝑥
≤ 10.13.11
CNA
mattermostmattermost
𝑥
≤ 11.3.4
CNA
Common Weakness Enumeration
References
https://mattermost.com/security-updates