CVE-2026-19076mediumCWE-863

CVE-2026-19076: medium-severity vulnerability in Mattermost

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

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13Vexday Risk Score

No sign of exploitation. No public exploitation artifact known so far.

ssvc Trackcvss 4.4epss 0.2%
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
CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:H/A:N
Affected products
Mattermost · Mattermost
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