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CVE-2026-4915

🔶 medium
🔍 Scan for this CVE
Summary

Mattermost versions 11.6.x <= 11.6.0, 11.5.x <= 11.5.3, 11.4.x <= 11.4.4, 10.11.x <= 10.11.14 fail to filter nil elements from outgoing webhook attachment payloads before processing, which allows an authenticated user to cause a denial of service (server process termination) via a crafted webhook callback response containing a null attachment entry.. Mattermost Advisory ID: MMSA-2026-00641

CVSS Score
6.5
Medium
EPSS Score
0.1
Exploit Probability
Published Date
2026-05-25
First Seen: 2026-05-27
📊 Relative Risk Intelligence

This CVE is Lower Risk - more severe than 47.7% of all 336,041 vulnerabilities in our database.

#175,688
Below average severity
Severity Percentile
🎯 CISA SSVC Assessment Updated: May 26, 2026
🔍 Exploitation Status
None
No known exploits
⚙️ Automatable
NO
Requires human interaction
💥 Technical Impact
Partial
Limited system impact
🏆 Discovered By
daw10
SSVC data provided by CISA
Last Modified 2026-06-01
Source NVD 🔗
CVSS Vector 3.1 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
CWE IDs (Weakness Types)
CWE-754

📦 Affected Products 4

Vendor Product Status Affected Versions
mattermost mattermost_server Affected
> 10.11.0 < 10.11.15
mattermost mattermost_server Affected
> 11.4.0 < 11.4.5
mattermost mattermost_server Affected
> 11.5.0 < 11.5.4
mattermost mattermost_server Affected
> 11.6.0 < 11.6.1

🔗 References 1

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

🔗 Related CVEs 6

CVE ID Severity CVSS EPSS Summary Published
CVE-2026-10085 🔶 medium 5.4 0.2 Mattermost versions 11.7.x <= 11.7.2, 11.6.x <= 11.6.4, 10.11.x <= 10.11.19 fail to restrict the group_constrained chann... 2026-07-13
CVE-2026-10103 🔶 medium 4.3 0.2 Mattermost versions 11.7.x <= 11.7.2, 11.6.x <= 11.6.4, 10.11.x <= 10.11.19 fail to verify post ownership in the shared ... 2026-07-13
CVE-2026-10106 🔶 medium 6.5 0.2 Mattermost versions 11.7.x <= 11.7.2, 11.6.x <= 11.6.4, 10.11.x <= 10.11.19 fail to verify that the channel referenced i... 2026-07-13
CVE-2026-6850 🔶 medium 6.5 0.2 Mattermost versions 11.7.x <= 11.7.2, 11.6.x <= 11.6.4, 10.11.x <= 10.11.19 fail to validate the length and content of m... 2026-07-13
CVE-2026-9571 🔶 medium 5.9 0.2 Mattermost versions 11.7.x <= 11.7.2, 11.6.x <= 11.6.4, 10.11.x <= 10.11.19 fail to invalidate OAuth refresh tokens upon... 2026-07-13
CVE-2026-9597 🔶 medium 5.4 0.1 Mattermost versions 11.7.x <= 11.7.2, 11.6.x <= 11.6.4 fail to verify whether a guest account is deactivated before crea... 2026-07-13
These CVEs affect the same products