CVE-2026-6340

EUVD-2026-30744
Mattermost versions 11.5.x <= 11.5.1, 10.11.x <= 10.11.13, 11.4.x <= 11.4.3 fail to validate 7zip archive structure before processing which allows an authenticated attacker to cause server memory exhaustion and denial of service via uploading a specially crafted 7zip file with excessive folder declarations.. Mattermost Advisory ID: MMSA-2026-00573
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:N/A:L
Base Score
CVSS 3.x
EPSS Score
Percentile: 11%
Affected Products (NVD)
VendorProductVersion
mattermostmattermost_server
10.11.0 ≤
𝑥
< 10.11.14
mattermostmattermost_server
11.4.0 ≤
𝑥
< 11.4.4
mattermostmattermost_server
11.5.0 ≤
𝑥
< 11.5.2
𝑥
= Vulnerable software versions
Early Detection
Affected products identified ahead of NVD analysis through intelligence sources.
VendorProductVersionSource
mattermostmattermost
11.5.0 ≤
𝑥
≤ 11.5.1
CNA
mattermostmattermost
10.11.0 ≤
𝑥
≤ 10.11.13
CNA
mattermostmattermost
11.4.0 ≤
𝑥
≤ 11.4.3
CNA
Common Weakness Enumeration
References
https://mattermost.com/security-updates