CVE-2026-86348 MEDIUM

CVE-2026-86348: MS Calendar plugin: unrecovered handler panics from malformed post-action requests could crash the plugin process

Vendor Mattermost
Product Mattermost
Weakness CWE-704
Published September 14, 2026
Last update September 14, 2026
View on NVD All CVEs

CVSS base score

4.3/10
Attack vector Network
Attack complexity Low
Privileges required Low
User interaction None
Confidentiality None
Integrity None

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L

What the vulnerability does

01Description

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

Key dates

02Disclosure timeline

September 14, 2026 CVE published