What is CVE-2026-3114?

CVE-2026-3114 is a medium-severity vulnerability in Mattermost, classified under Improper Handling of Highly Compressed Data (Data Amplification). CVSS score: 6.5/10. Published 2026-03-26.

How severe is CVE-2026-3114?

Medium severity. CVSS v3 base score is 6.5 out of 10.

Vulnerability in Mattermost

CVE-2026-3114

Mattermost versions 11.4.x <= 11.4.0, 11.3.x <= 11.3.1, 11.2.x <= 11.2.3, 10.11.x <= 10.11.11 fail to validate decompressed archive entry sizes during file extraction which allows authenticated users with file upload permissions to cause a…

EPSS: 0.000 (4.3th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H.

Affected products

Mattermost — versions 11.4.0, 11.3.0, 11.2.0

Weakness classification (CWE)

CWE-409 — Improper Handling of Highly Compressed Data (Data Amplification)

References

MMSA-2026-00598 (vendor-advisory)

Frequently asked questions

What is CVE-2026-3114?: CVE-2026-3114 is a medium-severity vulnerability in Mattermost, classified under Improper Handling of Highly Compressed Data (Data Amplification). CVSS score: 6.5/10. Published 2026-03-26.
How severe is CVE-2026-3114?: Medium severity. CVSS v3 base score is 6.5 out of 10.