---
id: CVE-2026-19541
title: >-
  Mattermost versions 11.9.x <= 11.9.1, 11.8.x <= 11.8.5, 11.7.x <= 11.7.10,
  11.10.x <= 11.10.1 fail to require re-entry of the stored client secret when
  validating an outgoing OAuth connection, which allows an authenticated user
  with perm…
summary: >-
  Mattermost versions 11.9.x <= 11.9.1, 11.8.x <= 11.8.5, 11.7.x <= 11.7.10,
  11.10.x <= 11.10.1 fail to require re-entry of the stored client secret when
  validating an outgoing OAuth connection, which allows an authenticated user
  with perm…
severity: medium
cvss: 6.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N'
cwe:
  - CWE-201
vendor: Mattermost
product: Mattermost
affected:
  - Mattermost >= 11.9.0 <= 11.9.1
  - Mattermost >= 11.8.0 <= 11.8.5
  - Mattermost >= 11.7.0 <= 11.7.10
  - Mattermost >= 11.10.0 <= 11.10.1
published: '2026-10-16'
updated: '2026-10-16'
sourceUpdated: '2026-10-16T19:23:18.623'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-19541'
references:
  - url: 'https://mattermost.com/security-updates'
    label: responsibledisclosure@mattermost.com
tags:
  - nvd
  - cve.org
epss: 0.00219
epssPercentile: 0.12286
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-10-16T12:03:05.371317Z'
ingestedAt: '2026-10-16T08:02:23.129Z'
---

## Overview

Mattermost versions 11.9.x <= 11.9.1, 11.8.x <= 11.8.5, 11.7.x <= 11.7.10, 11.10.x <= 11.10.1 fail to require re-entry of the stored client secret when validating an outgoing OAuth connection, which allows an authenticated user with permission to manage outgoing OAuth connections to obtain the secret via pointing the token URL at an attacker-controlled endpoint and triggering validation.. Mattermost Advisory ID: MMSA-2026-00761

## Remediation

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