mattermost mattermost CVE-2026-86348 is a vulnerability in MatterMost
Published on September 14, 2026

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

Vendor Advisory NVD

Vulnerability Analysis

CVE-2026-86348 is exploitable with network access, and requires small amount of user privileges. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality and integrity, and a small impact on availability.

Attack Vector:
NETWORK
Attack Complexity:
LOW
Privileges Required:
LOW
User Interaction:
NONE
Scope:
UNCHANGED
Confidentiality Impact:
NONE
Integrity Impact:
NONE
Availability Impact:
LOW

Weakness Type

Incorrect Type Conversion or Cast

The software does not correctly convert an object, resource, or structure from one type to a different type.


Products Associated with CVE-2026-86348

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MatterMost
 

Affected Versions

Mattermost: