CVE-2026-6340CWE-789

CVE-2026-6340

Medium · published May 18, 2026

CVSS v3.1
4.3
EPSS
0%
Percentile
14.3
In the wild
Unconfirmed
What it is

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

The record
Technical detail
CVSS v3.1
4.3 · MEDIUM
Vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
CVSS v4.0
Not supplied
EPSS
0.00240 · 14.3th percentile
Weakness
CWE-789 · Memory Allocation with Excessive Size Value
Published
2026-05-18T12:16Z
Affected products (3)
ProductVersionsFixed in
mattermost/mattermost_server≥ 10.11.0, < 10.11.1410.11.14
mattermost/mattermost_server≥ 11.4.0, < 11.4.411.4.4
mattermost/mattermost_server≥ 11.5.0, < 11.5.211.5.2
References (1)
https://mattermost.com/security-updates · [email protected]
EPSS history
Timeline
  • 18 MAY 07:08Z
    Memory Exhaustion via Malicious 7zip File Upload
    cvelistv5