CVE-2026-6333: mattermost server from 10.11.0 (inclusive), before 10.11.14 (exclusive), from 11.5.0 (inclusive), before 11.5.2…

Affected technology

mattermost server · from 10.11.0 (inclusive), before 10.11.14 (exclusive)
mattermost

mattermost server · from 11.5.0 (inclusive), before 11.5.2 (exclusive)
mattermost

Mattermost · 11.5.0 through 11.5.1, 10.11.0 through 10.11.13
Mattermost

Description’s affected range: versions 11.5.x <= 11.5.1

Component: Not specified by the source

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

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

What an attacker can do

The source says mattermost versions 11.5.x <= 11.5.1, 10.11.x <= 10.11.13 fail to validate the Host header when constructing response URLs for custom slash commands which allows an authenticated attacker to redirect slash command responses to an attacker-controlled server via a spoofed Host header. Vendor/CNA’s CVSS 3.1 assessment (base score 3.5/10) rates confidentiality and availability impact as none; integrity impact as low. NVD’s CVSS 3.1 assessment (base score 5.0/10) rates confidentiality and availability impact as none; integrity impact as low.