Vulnerability · Published Jul 13, 2026 · Assigned by Mattermost
CVE-2026-9597Deactivated guest accounts can authenticate via magic-link token in Mattermost REST API login endpoint
Medium 5.4
In plain English
A medium-severity security flaw in Mattermost from Mattermost. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 14% of all known vulnerabilities).
Severity (CVSS 3.1)5.4Medium
Exploit odds (30 days)0.2%top 86.1% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official 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
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Mattermost | Mattermost | 11.7.0 – through 11.7.211.6.0 – through 11.6.4 |
Weakness: CWE-305 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N
References
- MMSA-2026-00681 vendor-advisory