CVE-2026-19076

published 2026-10-16

CVE-2026-19076: 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…

Priority P4 25 medium 4.4 CVSS 3.1

AV N AC H PR H UI N S U C N I H A N

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

Affected

4 ranges

Vendor	Product	Version range	Fixed in
mattermost	mattermost	11.10.0 – 11.10.0	—
mattermost	mattermost	11.7.0 – 11.7.9	—
mattermost	mattermost	11.8.0 – 11.8.5	—
mattermost	mattermost	11.9.0 – 11.9.1	—

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CWE-863