Skip to content

CVE-20XX-?

CVE-2026-6340

4.3 MEDIUM 0.2% exploit odds Fix listed Denial of service Server

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

At a glance

Exploitability: Can be exploited over the network with a low-privilege account. Limited direct impact.
Exploit odds: 0.2% chance of exploitation in the next 30 days (EPSS).
Fix: A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

2026-05-18 08:16 UTC PublishedDisclosed publicly on CVE.org and NVD
2026-10-14 20:10 UTC Last updatedMost recent change to the record

Details

Published: 2026-05-18 08:16 UTC
Last modified: 2026-10-14 20:10 UTC
Exploit probability: 0.2% · EPSS, next 30 days
Weakness: CWE-789
Record status: Analyzed

Affected

Mattermost Server < 10.11.14
Mattermost Server < 11.4.4
Mattermost Server < 11.5.2

Attack profile CVSS 3.1 · 4.3

Attack vector: Network
Complexity: Low
Privileges needed: Low
User interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: None
Availability: Low

Raw vector

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

Meme: I wake up, CVE-2026-6340

Download Square Reddit

Fix and advisories

https://mattermost.com/security-updates

References

https://mattermost.com/security-updates

NVD record · CVE.org record