What is CVE-2026-26233?

CVE-2026-26233 is a medium-severity vulnerability in Mattermost, classified under Uncontrolled Resource Consumption. CVSS score: 4.3/10. Published 2026-03-25.

How severe is CVE-2026-26233?

Medium severity. CVSS v3 base score is 4.3 out of 10.

Resource exhaustion in Mattermost

CVE-2026-26233

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 rate limit login requests which allows unauthenticated remote attackers to cause denial of service (server crash and restart) via HTTP/2…

Vulnerability class: DoS (Denial of Service)

EPSS: 0.001 (30.9th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 4.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L.

Affected products

Mattermost — versions 11.4.0, 11.3.0, 11.2.0

Weakness classification (CWE)

CWE-400 — Uncontrolled Resource Consumption

References

MMSA-2025-00566 (vendor-advisory)

Frequently asked questions

What is CVE-2026-26233?: CVE-2026-26233 is a medium-severity vulnerability in Mattermost, classified under Uncontrolled Resource Consumption. CVSS score: 4.3/10. Published 2026-03-25.
How severe is CVE-2026-26233?: Medium severity. CVSS v3 base score is 4.3 out of 10.