CVE-2026-5163 Missing authorization check in AI message rewrite endpoint allows access to private thread content

Mattermost versions 11.5.x = 11.5.1 fail to verify channel membership when processing AI-assisted message rewrites which allows an authenticated attacker to read the content of threads in private channels and direct messages they do not have access to via a crafted request to the post rewrite...

EUVD-2026-12516

Mattermost versions 10.11.x = 10.11.10 Fail to invalidate cached permalink preview data when a user loses channel access which allows the user to continue viewing private channel content via previously cached permalink previews until cache reset or relogin.. Mattermost Advisory ID: MMSA-2026-0058...

Mattermost has an Incorrect Authorization vulnerability

Mattermost versions 10.5.x = 10.5.10, 10.11.x = 10.11.2 fail to properly validate guest user permissions when adding channel members which allows guest users to add any team members to their private channels via the /api/v4/channels/channelid/members endpoint...

EUVD-2023-32055

Malicious code in bioql PyPI...

EUVD-2023-0969

Malicious code in bioql PyPI...

Missing Authentication for Critical Function

Overview github.com/mattermost/mattermost/server/channels/app is a private-cloud Slack alternative Affected versions of this package are vulnerable to Missing Authentication for Critical Function in the deduplicateCreatePost method. An attacker can access posts in private channels without proper...

GHSA-7H34-9CHR-58QH Mattermost Missing Authentication for Critical Function

Mattermost versions 10.5.x = 10.5.6, 10.8.x = 10.8.1, 10.7.x = 10.7.3, 9.11.x = 9.11.16 fail to verify authorization when retrieving cached posts by PendingPostID which allows an authenticated user to read posts in private channels they don't have access to via guessing the PendingPostID of...

CVE-2025-6226

Mattermost versions 10.5.x = 10.5.6, 10.8.x = 10.8.1, 10.7.x = 10.7.3, 9.11.x = 9.11.16 fail to verify authorization when retrieving cached posts by PendingPostID which allows an authenticated user to read posts in private channels they don't have access to via guessing the PendingPostID of...

CVE-2025-6226 IDOR in CreatePost API allows for timeboxed message disclosure

Mattermost versions 10.5.x = 10.5.6, 10.8.x = 10.8.1, 10.7.x = 10.7.3, 9.11.x = 9.11.16 fail to verify authorization when retrieving cached posts by PendingPostID which allows an authenticated user to read posts in private channels they don't have access to via guessing the PendingPostID of...

CVE-2025-47871

Mattermost versions 10.5.x = 10.5.5, 9.11.x = 9.11.15, 10.8.x = 10.8.0, 10.7.x = 10.7.2, 10.6.x = 10.6.5 fail to properly validate channel membership when retrieving playbook run metadata, allowing authenticated users who are playbook members but not channel members to access sensitive informatio...

Mattermost Incorrect Authorization vulnerability

Mattermost versions 10.5.x = 10.5.5, 9.11.x = 9.11.15, 10.8.x = 10.8.0, 10.7.x = 10.7.2, 10.6.x = 10.6.5 fail to properly validate channel membership when retrieving playbook run metadata, allowing authenticated users who are playbook members but not channel members to access sensitive informatio...

CVE-2025-47871 Mattermost Playbooks exposes private channel metadata to unauthorized users via run metadata API

Mattermost versions 10.5.x = 10.5.5, 9.11.x = 9.11.15, 10.8.x = 10.8.0, 10.7.x = 10.7.2, 10.6.x = 10.6.5 fail to properly validate channel membership when retrieving playbook run metadata, allowing authenticated users who are playbook members but not channel members to access sensitive informatio...

CVE-2023-1774

When processing an email invite to a private channel on a team, Mattermost fails to validate the inviter's permission to that channel, allowing an attacker to invite themselves to a private channel...

BIT-MATTERMOST-2025-27715

Mattermost versions 9.11.x = 9.11.8 fail to prompt for explicit approval before adding a team admin to a private channel, which team admins to joining private channels via crafted permalink links without explicit consent from them...

GO-2025-3555 Mattermost fail to prompt for explicit approval before adding a team admin to a private channel in github.com/mattermost/mattermost-server

Mattermost fail to prompt for explicit approval before adding a team admin to a private channel in github.com/mattermost/mattermost-server...

Mattermost fail to prompt for explicit approval before adding a team admin to a private channel

Mattermost versions 9.11.x = 9.11.8 fail to prompt for explicit approval before adding a team admin to a private channel, which team admins to joining private channels via crafted permalink links without explicit consent from them...

GHSA-CW7Q-5CGC-H3H9 Mattermost fail to prompt for explicit approval before adding a team admin to a private channel

Mattermost versions 9.11.x = 9.11.8 fail to prompt for explicit approval before adding a team admin to a private channel, which team admins to joining private channels via crafted permalink links without explicit consent from them...

CVE-2025-27715 Auto-Enrollment of Team Admins into Private Channels without explicit consent

Mattermost versions 9.11.x = 9.11.8 fail to prompt for explicit approval before adding a team admin to a private channel, which team admins to joining private channels via crafted permalink links without explicit consent from them...

Mattermost 安全漏洞

Mattermost is an open source collaboration platform from Mattermost, Inc. in the United States. A security vulnerability exists in Mattermost version 9.11.8 and earlier, which stems from failing to prompt for explicit approval before adding team administrators to a private channel, allowing team...

Improper Access Control

Mattermost is vulnerable to Improper Access Control. The vulnerability is due to improper filtering of channel data when ElasticSearch is enabled, allowing users to access private channel names by using cmd+K/ctrl+K...