CVE-2026-3590

EUVD-2026-22915
Mattermost versions 10.11.x <= 10.11.12, 11.5.x <= 11.5.0, 11.4.x <= 11.4.2, 11.3.x <= 11.3.2 fail to enforce atomic single-use consumption of guest magic link tokens, which allows an attacker with access to a valid magic link to establish multiple independent authenticated sessions via concurrent requests.. Mattermost Advisory ID: MMSA-2026-00624
TOCTOU
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
MattermostCNA
6.5 MEDIUM
NETWORK
LOW
NONE
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
Base Score
CVSS 3.x
EPSS Score
Percentile: 11%
Affected Products (NVD)
VendorProductVersion
mattermostmattermost_server
10.11.0 ≤
𝑥
< 10.11.13
mattermostmattermost_server
11.3.0 ≤
𝑥
< 11.3.3
mattermostmattermost_server
11.4.0 ≤
𝑥
< 11.4.3
mattermostmattermost_server
11.5.0 ≤
𝑥
< 11.5.1
𝑥
= Vulnerable software versions
Early Detection
Affected products identified ahead of NVD analysis through intelligence sources.
VendorProductVersionSource
mattermostmattermost
10.11.0 ≤
𝑥
≤ 10.11.12
CNA
mattermostmattermost
𝑥
≤ 11.5.0
CNA
mattermostmattermost
11.4.0 ≤
𝑥
≤ 11.4.2
CNA
mattermostmattermost
11.3.0 ≤
𝑥
≤ 11.3.2
CNA
Common Weakness Enumeration
References
https://mattermost.com/security-updates