CVE-2026-3115

EUVD-2026-16245
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 apply view restrictions when retrieving group member IDs, which allows authenticated guest users to enumerate user IDs outside their allowed visibility scope via the group retrieval endpoint.. Mattermost Advisory ID: MMSA-2026-00594
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:L/I:N/A:N
Base Score
CVSS 3.x
EPSS Score
Percentile: 10%
Affected Products (NVD)
VendorProductVersion
mattermostmattermost_server
10.11.0 ≤
𝑥
< 10.11.11
mattermostmattermost_server
11.2.0 ≤
𝑥
< 11.2.3
mattermostmattermost_server
11.3.0 ≤
𝑥
< 11.3.2
mattermostmattermost_server
11.4.0
𝑥
= Vulnerable software versions
Early Detection
Affected products identified ahead of NVD analysis through intelligence sources.
VendorProductVersionSource
mattermostmattermost
11.2.0 ≤
𝑥
≤ 11.2.2
CNA
mattermostmattermost
10.11.0 ≤
𝑥
≤ 10.11.10
CNA
mattermostmattermost
𝑥
≤ 11.4.0
CNA
mattermostmattermost
11.3.0 ≤
𝑥
≤ 11.3.1
CNA
Common Weakness Enumeration
References
https://mattermost.com/security-updates