CVE-2026-9597 json
Deactivated guest accounts can authenticate via magic-link token in Mattermost REST API login endpoint
published 2026-07-13 3 mo ago modified 2026-07-13 3 mo ago also EUVD-2026-43315
- cvss
- 5.4
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.2%
- EPSS 0.2% chance of exploitation in 30 days, percentile 13%
- public exploits
- 0
- none known
Summary
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
Patch / fix
- Mattermost Mattermost 11.6.5, 11.7.3, 11.8.0
CISA SSVC
- Exploitation
- none
- Automatable
- no
- Technical impact
- partial
- Assessed
- 3 mo ago
Exploit prediction
0.23% chance of exploitation in the next 30 days, higher than 13% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 5.4 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N |
Affected products
- Mattermost Mattermost
Classification
- Weakness
-
- CWE-305 Authentication Bypass by Primary Weakness
References
-
mattermost.com
/security-updates
vendor-advisory
Sources
- CVE List CVE-2026-9597
- NVD CVE-2026-9597
Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.