An issue was discovered in Mattermost Server before 4.0.0, 3.10.2, and 3.9.2, when Single Sign-On OAuth2 is used. An attacker could claim somebody else's account.
https://mattermost.com/security-updates/
Source: Mitre, NVD
Published: 2020-06-19
Updated: 2026-06-17
Base Score: 4.9
Vector: CVSS2#AV:N/AC:M/Au:S/C:P/I:P/A:N
Severity: Medium
Base Score: 8.1
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
Severity: High
EPSS: 0.00209