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
CVSS 5.7EPSS 0.18%Risk 0.58
View source- Published
- 2026-03-25 17:16:56
- Affected versions
- <= 11.4.0, <= 11.3.1, <= 11.2.3, <= 10.11.11
- Type
- Core software
- Vector
- CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:H/I:H/A:N