CVE-2026-27656 | BDVDB-2026-322804 Detail
MattermostMattermost
Description#
Mattermost versions 11.4.x <= 11.4.0, 11.3.x <= 11.3.1, 11.2.x <= 11.2.3, 10.11.x <= 10.11.11 fail to properly validate user identity in the OpenID {{IsSameUser()}} comparison logic, which allows an attacker to take over arbitrary user accounts via an overly permissive substring matching flaw in the user discovery flow.. Mattermost Advisory ID: MMSA-2026-00590
Impact#
Per CVSS v3.1: confidentiality impact high, integrity impact high, availability impact none. Attack vector: network.
Weaknesses#
- CWE-303 Incorrect Implementation of Authentication Algorithm
References#
Exploit#
No public exploit known
History#
- Version 1Record published in the CVE List.
- Version 2Most recent update recorded in the CVE List.