CVE-2026-3590

Mattermost versions 10.11.x <= 10.11.12, 11.5.x <= 11.5.0, 11.4.x <= 11.4.2, 11.3.x <= 11.3.2 fail to enforce atomic single-use consumption of guest magic link tokens, which allows an attacker with access to a valid magic link to establish multiple independent authenticated sessions via concurrent requests.. Mattermost Advisory ID: MMSA-2026-00624

Score

CVSS 3.1 6.5 Medium

Status

Analyzed - responsibledisclosure@mattermost.com

Published

2026-04-15

Last modified

2026-04-15

Weaknesses

CWE-367

Affected products

• Mattermost (Mattermost)
• Mattermost Server (Mattermost)

References

• https://mattermost.com/security-updates