CVE-2026-27656
Published: Mar 25, 2026
Modified: Mar 26, 2026
CVSS v3.1
5.7
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
| Vendor | Product | Versions |
|---|---|---|
Mattermost | Mattermost | affected 11.4.0 - <= 11.4.0affected 11.3.0 - <= 11.3.1affected 11.2.0 - <= 11.2.3affected 10.11.0 - <= 10.11.11unaffected 11.5.0+4 more versions |
Weaknesses (CWE)
CVSS v3.1 Details
CVSS v3.1 Vector
CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:H/I:H/A:N
Attack Vector
Attack Complexity
Privileges Required
User Interaction
Scope
Confidentiality
Integrity
Availability
References
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