CVE-2026-95666: mattermost server from 11.7.0 (inclusive), before 11.7.11 (exclusive), from 11.8.0 (inclusive), before 11.8.6…

Affected technology

mattermost server · from 11.7.0 (inclusive), before 11.7.11 (exclusive)
mattermost

mattermost server · from 11.8.0 (inclusive), before 11.8.6 (exclusive)
mattermost

mattermost server · from 11.9.0 (inclusive), before 11.9.2 (exclusive)
mattermost

mattermost server · from 11.10.0 (inclusive), before 11.10.2 (exclusive)
mattermost

Mattermost · 11.9.0 through 11.9.1, 11.8.0 through 11.8.5, 11.7.0 through 11.7.10, 11.10.0 through 11.10.1
Mattermost

Description’s affected range: versions 11.9.x <= 11.9.1

Component: Not specified by the source

Attack conditions (Vendor/CNA, CVSS 3.1): Network (remote) · Low privileges required · No user interaction required

What an attacker can do

An authenticated user can cause excessive database load via a crafted request to {{POST /api/v4/posts/ids/reactions}}. Vendor/CNA’s CVSS 3.1 assessment (base score 4.3/10) rates confidentiality and integrity impact as none; availability impact as low.