What is CVE-2026-86348?

CVE-2026-86348 is a medium-severity vulnerability in Mattermost, classified under Incorrect Type Conversion or Cast. CVSS score: 4.3/10. Published 2026-09-14.

How severe is CVE-2026-86348?

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

Vulnerability in Mattermost

CVE-2026-86348

Mattermost versions <=11.9 11.0.9 11.4.8 11.7.7 10.22.11.0 fail to recover from handler panics, which allows an authenticated user to crash the plugin via a post-action request with an unexpected field type.. Mattermost Advisory ID: MMSA-2026-00701

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

Weakness classification (CWE)

CWE-704 — Incorrect Type Conversion or Cast

References

responsibledisclosure@mattermost.com (vendor-advisory)

Frequently asked questions

What is CVE-2026-86348?: CVE-2026-86348 is a medium-severity vulnerability in Mattermost, classified under Incorrect Type Conversion or Cast. CVSS score: 4.3/10. Published 2026-09-14.
How severe is CVE-2026-86348?: Medium severity. CVSS v3 base score is 4.3 out of 10.