CVE-2026-19076

Mattermost fails to reject OAuth application sessions in account type switch, allowing account takeover via bearer token

State: Published
Severity: 4.4 Medium
Published: Oct 16, 2026
Updated: Oct 16, 2026
Reserved: Aug 6, 2026

Read the record on cve.org

Description

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

Scores

CVSS	Score	Vector	Source
3.1	4.4 Medium	CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:H/A:N	Mattermost

Weaknesses

CWE-863 Incorrect Authorization

Affected Products

Product	Versions
MattermostMattermost	11.10.0 through 11.10.0Affected 11.7.0 through 11.7.9Affected 11.9.0 through 11.9.1Affected 11.8.0 through 11.8.5Affected 11.11.0Not affected 11.10.1Not affected 11.7.10Not affected 11.9.2Not affected 11.8.6Not affected

References

MMSA-2026-00758vendor-advisory

Every record here comes from the CVE Program’s CVE List. © 1999–2026 The MITRE Corporation. CVE is a registered trademark of The MITRE Corporation. The records are reproduced under the CVE Program terms of use.