---
id: CVE-2026-6341
title: >-
  Mattermost Plugins versions <=11.5 11.1.5 10.13.11 11.3.4.0 fail to have
  API-level checks on which groups the user can create issues or attach comments
  to which allows a user that is member of multiple groups to create issues to a
  locked…
summary: >-
  Mattermost Plugins versions <=11.5 11.1.5 10.13.11 11.3.4.0 fail to have
  API-level checks on which groups the user can create issues or attach comments
  to which allows a user that is member of multiple groups to create issues to a
  locked…
severity: medium
cvss: 4.3
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N'
cwe:
  - CWE-863
vendor: mattermost
product: mattermost_server
affected:
  - 'mattermost_server >= 10.13.0, <= 10.13.11'
  - 'mattermost_server >= 11.1.0, <= 11.1.5'
  - 'mattermost_server >= 11.3.0, <= 11.3.4'
published: '2026-05-18'
updated: '2026-10-14'
sourceUpdated: '2026-10-14T20:10:00.190'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-6341'
references:
  - url: 'https://mattermost.com/security-updates'
    label: responsibledisclosure@mattermost.com
tags:
  - nvd
epss: 0.00254
epssPercentile: 0.1578
ingestedAt: '2026-10-14T20:53:12.297Z'
---

## Overview

Mattermost Plugins versions <=11.5 11.1.5 10.13.11 11.3.4.0 fail to have API-level checks on which groups the user can create issues or attach comments to which allows a user that is member of multiple groups to create issues to a locked group via direct API requests. Mattermost Advisory ID: MMSA-2026-00602

## Affected

- `mattermost_server >= 10.13.0, <= 10.13.11`
- `mattermost_server >= 11.1.0, <= 11.1.5`
- `mattermost_server >= 11.3.0, <= 11.3.4`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.