What is CVE-2026-22880?

CVE-2026-22880 is a medium-severity vulnerability in Mattermost, classified under Cross-Site Request Forgery (CSRF). CVSS score: 6.1/10. Published 2026-05-21.

How severe is CVE-2026-22880?

Medium severity. CVSS v3 base score is 6.1 out of 10.

CSRF in Mattermost

CVE-2026-22880

Mattermost Mobile Apps versions <=2.37 11.4 2.0.37 11.0.4 11.1.3 11.3.2 10.11.11.0 fail to properly validate the SSO authentication callback origin which allows an attacker controlling a malicious Mattermost server to steal user credentials for a legitimate Mattermost server via relaying the SSO code exchange flow through the mobile application. Mattermost Advisory ID: MMSA-2025-00564

Vulnerability class: CSRF (Cross-Site Request Forgery)

Published 2026-05-21 · last modified 2026-08-06.

CVSS v3 metric

CVSS v3 base score 6.1 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:N/A:N.

EPSS exploit prediction

EPSS: 0.001 (1.5th percentile), scored 2026-09-28.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 2nd percentile — 1.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.001 · newest: 0.001 · change: 0.000

Affected products

Mattermost — versions 0, 2.38.0, 11.5.0
Mattermost Mobile

Weakness classification (CWE)

CWE-352 — Cross-Site Request Forgery (CSRF)

References

mattermost.com/security-updates (vendor-advisory, Vendor Advisory)

Frequently asked questions

What is CVE-2026-22880?: CVE-2026-22880 is a medium-severity vulnerability in Mattermost, classified under Cross-Site Request Forgery (CSRF). CVSS score: 6.1/10. Published 2026-05-21.
How severe is CVE-2026-22880?: Medium severity. CVSS v3 base score is 6.1 out of 10.