CVE-2026-19603: 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

Affected technology

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 learn the channel ID of a private channel another user is actively viewing via the status endpoints, without being a member of that channel. Vendor/CNA’s CVSS 3.1 assessment (base score 4.3/10) rates confidentiality impact as low; integrity and availability impact as none.