CVE-2026-9597

Deactivated guest accounts can authenticate via magic-link token in Mattermost REST API login endpoint

State: Published
Severity: 5.4 Medium
Published: Jul 13, 2026
Updated: Jul 13, 2026
Reserved: May 26, 2026

Description

Mattermost versions 11.7.x <= 11.7.2, 11.6.x <= 11.6.4 fail to verify whether a guest account is deactivated before creating a session in the magic-link token login path, which allows a deactivated guest user to obtain a fully functional session via a magic-link token issued prior to deactivation.. Mattermost Advisory ID: MMSA-2026-00681

Scores

CVSS	Score	Vector	Source
3.1	5.4 Medium	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N	Mattermost

Weaknesses

CWE-305 – Authentication Bypass by Primary Weakness

Affected Products

Product	Versions
MattermostMattermost	11.7.0 through 11.7.2Affected 11.6.0 through 11.6.4Affected 11.8.0Not affected 11.7.3Not affected 11.6.5Not affected

References

MMSA-2026-00681vendor-advisory

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