CVE-2026-96259 json
Mattermost server-side request forgery via OAuth endpoints configurable by a System Administrator
published 2026-09-22 47 d ago modified 2026-10-07 32 d ago also EUVD-2026-84869
- cvss
- 5.5
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.3%
- EPSS 0.3% chance of exploitation in 30 days, percentile 17%
- public exploits
- 0
- none known
Summary
Mattermost versions 11.9.x <= 11.9.1, 11.8.x <= 11.8.5, 11.7.x <= 11.7.10, 11.10.x <= 11.10.1 fail to apply the internal-connection filter to OAuth endpoint requests, which allows a System Administrator to make the server issue requests to internal network addresses and read the responses via the configured OAuth token and userinfo endpoints.. Mattermost Advisory ID: MMSA-2026-00776
Patch / fix
- Mattermost Mattermost 11.7.11, 11.8.6, 11.9.2, 11.10.2, 11.11.0
CISA SSVC
- Exploitation
- none
- Automatable
- no
- Technical impact
- partial
- Assessed
- 46 d ago
Exploit prediction
0.26% chance of exploitation in the next 30 days, higher than 17% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 5.5 | CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:L/I:L/A:N |
Affected products
- Mattermost Mattermost
Classification
- Weakness
-
- CWE-918 Server-Side Request Forgery
References
-
mattermost.com
/security-updates
vendor-advisory
Sources
- CVE List CVE-2026-96259
- NVD CVE-2026-96259
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