Incorrect Authorization

Overview Affected versions of this package are vulnerable to Incorrect Authorization via the API response process. An attacker can access sensitive information about team member roles by invoking various team API endpoints without having elevated permissions. Remediation Upgrade...

CVE-2026-3636

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 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 unauthorized privilege to demote users to guest status by exploiting this flaw while...

CVE-2026-26230

A permissions validation flaw has been discovered in mattermost server. Affected versions fail to properly validate permission requirements in the team member roles API endpoint which allows team administrators to demote members to guest role. Mitigation Mitigation for this issue is either not...

CVE-2026-26230 Team Admin Privilege Escalation to Demote Members to Guest

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 Team Admin Privilege Escalation to Demote Members to Guest

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...

PT-2026-25813

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...

Incorrect Authorization

Overview Affected versions of this package are vulnerable to Incorrect Authorization via the PUT /api/v4/teams/team-id/members/user-id/schemeRoles endpoint. An attacker can modify team member roles without proper authorization by sending crafted API requests. Remediation Upgrade...

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 via the PUT /api/v4/teams/team-id/members/user-id/schemeRoles endpoint. An attacker can modify team member roles without...

Improper Access Control

Mattermost Server is vulnerable to Improper Access Control. The vulnerability is due to improper validation when updating team member roles, allowing users with certain administrative privileges to demote other users to guest status through crafted HTTP requests...