CVE-2026-19076CWE-863broken-access-control

CVE-2026-19076

Medium · published October 16, 2026

CVSS v3.1
4.4
EPSS
0%
Percentile
9.0
In the wild
Unconfirmed
What it is

Mattermost versions 11.10.x <= 11.10.0, 11.7.x <= 11.7.9, 11.9.x <= 11.9.1, 11.8.x <= 11.8.5 fail to reject OAuth application sessions in the account type switch endpoint, which allows an attacker with a valid OAuth bearer token for a target user to permanently take over that user's SSO-backed account by setting an attacker-controlled password and detaching the account from its identity provider via a crafted request to POST /api/v4/users/login/switch.. Mattermost Advisory ID: MMSA-2026-00758

The record
Technical detail
CVSS v3.1
4.4 · MEDIUM
Vector
CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:H/A:N
CVSS v4.0
Not supplied
EPSS
0.00197 · 9.0th percentile
Weakness
CWE-863 · Incorrect Authorization
Published
2026-10-16T12:17Z
References (1)
https://mattermost.com/security-updates · [email protected]
EPSS history
Timeline
  • 17 OCT 03:28Z
    EPSS moved — → 0%
    epss
  • 16 OCT 07:11Z
    Mattermost fails to reject OAuth application sessions in account type switch, allowing account takeover via bearer token
    cvelistv5
  • 16 OCT 07:11Z
    Mattermost fails to reject OAuth application sessions in account type switch, allowing account takeover via bearer token
    cvelistv5