CVE-2026-19076
Mattermost fails to reject OAuth application sessions in account type switch, allowing account takeover via bearer token
CVSS Score
4.4
EPSS Score
0.0%
EPSS Percentile
0th
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
| CWE | CWE-863 |
| Vendor | mattermost |
| Product | mattermost |
| Published | Oct 16, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:H/A:N Attack Vector
Network
Attack Complexity
High
Privileges Required
High
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
None
Affected Versions
Mattermost / Mattermost
11.10.0 ≤ 11.10.0 11.7.0 ≤ 11.7.9 11.9.0 ≤ 11.9.1 11.8.0 ≤ 11.8.5
Credits
CERT PL