CVEvulnerability

CVE-2026-27656

6.1 MEDIUM Published 2026-03-25 Modified 2026-06-17 Official page ↗
Status
Analyzed
Published
2026-03-25
Last modified
2026-06-17
Assigner
[email protected]
CVSS 3.1 ([email protected])
5.7 MEDIUM — CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:H/I:H/A:N
CVSS 3.1 ([email protected])
6.1 MEDIUM — CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:U/C:H/I:H/A:N
Weaknesses
CWE-303

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

Affected configurations

• mattermost mattermost server (>= 10.11.0 < 10.11.12) • mattermost mattermost server (>= 11.2.0 < 11.2.4) • mattermost mattermost server (>= 11.3.0 < 11.3.2) • mattermost mattermost server (>= 11.4.0 < 11.4.1)

Related

Weakness · CWE (1)

  • CWE-303 Incorrect Implementation of Authentication Algorithm weakness

References