Vulnerability DatabaseCVE-2026-95666
Mend.io Vulnerability Database
The largest open source vulnerability database
What is a Vulnerability ID?
New vulnerability? Tell us about it!
CVE-2026-95666
Published:September 22, 2026
Updated:October 09, 2026
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 of the post ID array accepted by the bulk reactions endpoint which allows an authenticated user to cause excessive database load via a crafted request to {{POST /api/v4/posts/ids/reactions}}.. Mattermost Advisory ID: MMSA-2026-00771
Affected Packages
https://github.com/mattermost/mattermost.git (GITHUB):
Affected version(s) >=v11.9.0 <v11.9.2
Fix Suggestion:
Update to version v11.9.2
https://github.com/mattermost/mattermost.git (GITHUB):
Affected version(s) >=v11.7.0 <v11.7.11
Fix Suggestion:
Update to version v11.7.11
https://github.com/mattermost/mattermost.git (GITHUB):
Affected version(s) >=v11.10.0 <v11.10.2
Fix Suggestion:
Update to version v11.10.2
Related Resources (1)
https://mattermost.com/security-updates
Do you need more information?
Contact Us
CVSS v4
Base Score:
5.3
Attack Vector
NETWORK
Attack Complexity
LOW
Attack Requirements
NONE
Privileges Required
LOW
User Interaction
NONE
Vulnerable System Confidentiality
NONE
Vulnerable System Integrity
NONE
Vulnerable System Availability
LOW
Subsequent System Confidentiality
NONE
Subsequent System Integrity
NONE
Subsequent System Availability
NONE
CVSS v3
Base Score:
4.3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
LOW
Weakness Type (CWE)
Allocation of Resources Without Limits or Throttling
CWE-770
EPSS
Base Score:
0.37