---
id: CVE-2023-6202
aliases:
  - GHSA-85jj-c9jr-9jhx
title: Mattermost Improper Access Control vulnerability
summary: Mattermost Improper Access Control vulnerability
severity: medium
cvss: 4.3
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N'
vendor: mattermost
product: github.com/mattermost/mattermost/server/v8
ecosystem: go
affected:
  - 'github.com/mattermost/mattermost/server/v8 >= 9.1.0, < 9.1.1'
  - 'github.com/mattermost/mattermost/server/v8 >= 9.0.0, < 9.0.2'
  - github.com/mattermost/mattermost/server/v8 < 8.1.4
  - github.com/mattermost/mattermost-server/v6 < 7.8.13
patched:
  - github.com/mattermost/mattermost/server/v8 9.1.1
  - github.com/mattermost/mattermost/server/v8 9.0.2
  - github.com/mattermost/mattermost/server/v8 8.1.4
  - github.com/mattermost/mattermost-server/v6 7.8.13
published: '2023-11-27'
updated: '2026-09-10'
sourceUpdated: '2026-09-10T03:49:58.905302619Z'
source: OSV
sourceUrl: 'https://osv.dev/vulnerability/GHSA-85jj-c9jr-9jhx'
references:
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2023-6202'
  - url: 'https://github.com/mattermost/mattermost'
  - url: 'https://mattermost.com/security-updates'
tags:
  - osv
  - go
epss: 0.00443
epssPercentile: 0.37954
ingestedAt: '2026-09-12T03:13:01.766Z'
---

## Overview

Mattermost fails to perform proper authorization in the `/plugins/focalboard/api/v2/users` endpoint allowing an attacker who is a guest user and knows the ID of another user to get their information (e.g. name, surname, nickname) via Mattermost Boards.



## Affected packages

- `github.com/mattermost/mattermost/server/v8 >= 9.1.0, < 9.1.1`
- `github.com/mattermost/mattermost/server/v8 >= 9.0.0, < 9.0.2`
- `github.com/mattermost/mattermost/server/v8 < 8.1.4`
- `github.com/mattermost/mattermost-server/v6 < 7.8.13`

## Remediation

Upgrade to a patched release:

- `github.com/mattermost/mattermost/server/v8 9.1.1`
- `github.com/mattermost/mattermost/server/v8 9.0.2`
- `github.com/mattermost/mattermost/server/v8 8.1.4`
- `github.com/mattermost/mattermost-server/v6 7.8.13`