CVEFinder.io

CVE-2026-96259

🔶 medium
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

CVSS Score
5.5
Medium
EPSS Score
0.3
Exploit Probability
Published Date
2026-09-22
First Seen: 2026-09-24
📊 Relative Risk Intelligence

This CVE is Lower Risk - more severe than 31.3% of all 365,890 vulnerabilities in our database.

#251,398
Below average severity
Severity Percentile
🎯 CISA SSVC Assessment Updated: Sep 23, 2026
🔍 Exploitation Status
None
No known exploits
⚙️ Automatable
NO
Requires human interaction
💥 Technical Impact
Partial
Limited system impact
🏆 Discovered By
n1nj4sec
SSVC data provided by CISA
Last Modified 2026-10-07
Source NVD 🔗
CVSS Vector 3.1 CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:L/I:L/A:N
CWE IDs (Weakness Types)
CWE-918

📦 Affected Products 4

Vendor Product Status Affected Versions
mattermost mattermost_server Affected
> 11.10.0 < 11.10.2
mattermost mattermost_server Affected
> 11.7.0 < 11.7.11
mattermost mattermost_server Affected
> 11.8.0 < 11.8.6
mattermost mattermost_server Affected
> 11.9.0 < 11.9.2

🔗 References 1

https://mattermost.com/security-updates
Vendor Advisory

🔗 Related CVEs 6

CVE ID Severity CVSS EPSS Summary Published
CVE-2026-95666 🔶 medium 4.3 0.4 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 limit the length o... 2026-09-22
CVE-2026-96260 🔶 medium 6.5 0.4 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 enforce a request ... 2026-09-22
CVE-2026-10542 🔶 medium 5.0 0.1 Mattermost versions 11.9.x <= 11.9.0, 11.8.x <= 11.8.4, 11.7.x <= 11.7.7, 10.11.x <= 10.11.22 fail to validate channel a... 2026-09-14
CVE-2026-10556 🔶 medium 5.3 0.3 Mattermost versions 11.9.x <= 11.9.0, 11.8.x <= 11.8.4, 11.7.x <= 11.7.7, 10.11.x <= 10.11.22 fail to validate null entr... 2026-09-14
CVE-2026-11993 🔶 medium 4.3 0.2 Mattermost versions 11.9.x <= 11.9.0, 11.8.x <= 11.8.4, 11.7.x <= 11.7.7, 10.11.x <= 10.11.22 fail to properly enforce t... 2026-09-14
CVE-2026-12882 🔶 medium 4.3 0.2 Mattermost versions 11.9.x <= 11.9.0, 11.8.x <= 11.8.4, 11.7.x <= 11.7.7, 10.11.x <= 10.11.22 fail to parse Markdown aut... 2026-09-14
These CVEs affect the same products