Mattermost doesn't sanitize team member data when returned via API to users without elevated permissions

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 sanitize team member data when returned via API to users without elevated permissions which allows a user without permissions to get data about team members roles via invoking various team API...

Incorrect Authorization

Overview github.com/mattermost/mattermost/server/v8/channels/api4 is a platform for secure collaboration across the entire software development lifecycle Affected versions of this package are vulnerable to Incorrect Authorization via the API response process. An attacker can access sensitive...

Incorrect Authorization

Overview github.com/mattermost/mattermost/server/channels/app is a private-cloud Slack alternative Affected versions of this package are vulnerable to Incorrect Authorization due to insufficient validation of permission requirements in the team member roles API endpoint. An attacker can gain...

EUVD-2026-12518

Mattermost versions 10.11.x = 10.11.10 fail to properly validate permission requirements in the team member roles API endpoint which allows team administrators to demote members to guest role. Mattermost Advisory ID: MMSA-2025-00531...

CVE-2026-26230

Mattermost versions 10.11.x = 10.11.10 fail to properly validate permission requirements in the team member roles API endpoint which allows team administrators to demote members to guest role. Mattermost Advisory ID: MMSA-2025-00531...

CVE-2026-26230

Mattermost versions 10.11.x = 10.11.10 fail to properly validate permission requirements in the team member roles API endpoint which allows team administrators to demote members to guest role. Mattermost Advisory ID: MMSA-2025-00531...

EUVD-2025-25413

Malicious code in bioql PyPI...

Exercise your Incident Response Plan

So youve finally completed your Incident Response Plan. Youve named your team, defined roles, documented standard operating procedures, and establishing escalation processes. Heck, youve even got training material. So now what?...