CVE-2026-6340 MEDIUM

CVE-2026-6340: Memory Exhaustion via Malicious 7zip File Upload

Vendor Mattermost
Product Mattermost
Weakness CWE-789
Published May 18, 2026
Last update May 18, 2026
View on NVD All CVEs

CVSS base score

4.3/10
Attack vector Network
Attack complexity Low
Privileges required Low
User interaction None
Confidentiality None
Integrity None

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L

What the vulnerability does

01Description

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

Key dates

02Disclosure timeline

May 18, 2026 CVE published
May 18, 2026 Record updated