What is CVE-2026-3495?

CVE-2026-3495 is a low-severity vulnerability in Mattermost, classified under Cross-site Scripting. CVSS score: 3.8/10. Published 2026-05-18.

How severe is CVE-2026-3495?

Low severity. CVSS v3 base score is 3.8 out of 10.

XSS in Mattermost

CVE-2026-3495

Mattermost versions 11.5.x <= 11.5.1, 10.11.x <= 10.11.13 fail to escape some variables that could contain malicious content during error page composition which allows an attacker with access to edit some site configuration to execute some…

Vulnerability class: XSS (Cross-Site Scripting)

EPSS: 0.000 (9.0th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 3.8 (Low). Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:L/I:L/A:N.

Affected products

Mattermost — versions 11.5.0, 10.11.0, 11.6.0
Mattermost Mattermost_server

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

responsibledisclosure@mattermost.com (vendor-advisory, Vendor Advisory)

Frequently asked questions

What is CVE-2026-3495?: CVE-2026-3495 is a low-severity vulnerability in Mattermost, classified under Cross-site Scripting. CVSS score: 3.8/10. Published 2026-05-18.
How severe is CVE-2026-3495?: Low severity. CVSS v3 base score is 3.8 out of 10.