Vulnerabilities (CVE)

Filtered by vendor Mattermost Subscribe
Filtered by product Mattermost Server
Total 501 CVE
CVE Vendors Products Updated CVSS v2 CVSS v3
CVE-2026-27656 1 Mattermost 1 Mattermost Server 2026-06-17 N/A 5.7 MEDIUM
Mattermost versions 11.4.x <= 11.4.0, 11.3.x <= 11.3.1, 11.2.x <= 11.2.3, 10.11.x <= 10.11.11 fail to properly validate user identity in the OpenID {{IsSameUser()}} comparison logic, which allows an attacker to take over arbitrary user accounts via an overly permissive substring matching flaw in the user discovery flow.. Mattermost Advisory ID: MMSA-2026-00590
CVE-2026-26304 1 Mattermost 1 Mattermost Server 2026-06-17 N/A 4.3 MEDIUM
Mattermost versions 11.3.x <= 11.3.0, 11.2.x <= 11.2.2 fail to verify run_create permission for empty playbookId, which allows team members to create unauthorized runs via the playbook run API. Mattermost Advisory ID: MMSA-2025-00542
CVE-2026-26246 1 Mattermost 1 Mattermost Server 2026-06-17 N/A 4.3 MEDIUM
Mattermost versions 11.3.x <= 11.3.0, 11.2.x <= 11.2.2, 10.11.x <= 10.11.10 fail to bound memory allocation when processing PSD image files which allows an authenticated attacker to cause server memory exhaustion and denial of service via uploading a specially crafted PSD file. Mattermost Advisory ID: MMSA-2026-00572
CVE-2026-26233 1 Mattermost 1 Mattermost Server 2026-06-17 N/A 4.3 MEDIUM
Mattermost versions 11.4.x <= 11.4.0, 11.3.x <= 11.3.1, 11.2.x <= 11.2.3, 10.11.x <= 10.11.11 fail to rate limit login requests which allows unauthenticated remote attackers to cause denial of service (server crash and restart) via HTTP/2 single packet attack with 100+ parallel login requests.. Mattermost Advisory ID: MMSA-2025-00566
CVE-2026-26230 1 Mattermost 1 Mattermost Server 2026-06-17 N/A 3.8 LOW
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-2026-25783 1 Mattermost 1 Mattermost Server 2026-06-17 N/A 4.3 MEDIUM
Mattermost versions 11.3.x <= 11.3.0, 11.2.x <= 11.2.2, 10.11.x <= 10.11.10 fail to properly validate User-Agent header tokens which allows an authenticated attacker to cause a request panic via a specially crafted User-Agent header. Mattermost Advisory ID: MMSA-2026-00586
CVE-2026-25780 1 Mattermost 1 Mattermost Server 2026-06-17 N/A 4.3 MEDIUM
Mattermost versions 11.3.x <= 11.3.0, 11.2.x <= 11.2.2, 10.11.x <= 10.11.10 fail to bound memory allocation when processing DOC files which allows an authenticated attacker to cause server memory exhaustion and denial of service via uploading a specially crafted DOC file.. Mattermost Advisory ID: MMSA-2026-00581
CVE-2026-24692 1 Mattermost 1 Mattermost Server 2026-06-17 N/A 4.3 MEDIUM
Mattermost versions 11.3.x <= 11.3.0, 11.2.x <= 11.2.2, 10.11.x <= 10.11.10 fail to properly enforce read permissions in search API endpoints which allows guest users without read permissions to access posts and files in channels via search API requests. Mattermost Advisory ID: MMSA-2025-00554
CVE-2026-24458 1 Mattermost 1 Mattermost Server 2026-06-17 N/A 7.5 HIGH
Mattermost versions 11.3.x <= 11.3.0, 11.2.x <= 11.2.2, 10.11.x <= 10.11.10 fail to properly handle very long passwords, which allows an attacker to overload the server CPU and memory via executing login attempts with multi-megabyte passwords. Mattermost Advisory ID: MMSA-2026-00587
CVE-2026-22892 1 Mattermost 1 Mattermost Server 2026-06-17 N/A 4.3 MEDIUM
Mattermost versions 11.1.x <= 11.1.2, 10.11.x <= 10.11.9, 11.2.x <= 11.2.1 fail to validate user permissions when creating Jira issues from Mattermost posts, which allows an authenticated attacker with access to the Jira plugin to read post content and attachments from channels they do not have access to via the /create-issue API endpoint by providing the post ID of an inaccessible post.. Mattermost Advisory ID: MMSA-2025-00550
CVE-2026-22545 1 Mattermost 1 Mattermost Server 2026-06-17 N/A 3.1 LOW
Mattermost versions 10.11.x <= 10.11.10 fail to validate user's authentication method when processing account auth type switch which allows an authenticated attacker to change account password without confirmation via falsely claiming a different auth provider.. Mattermost Advisory ID: MMSA-2026-00583
CVE-2026-21388 1 Mattermost 1 Mattermost Server 2026-06-17 N/A 3.7 LOW
Mattermost Plugins versions <=2.3.1 fail to limit the request body size on the {{/lifecycle}} webhook endpoint which allows an authenticated attacker to cause memory exhaustion and denial of service via sending an oversized JSON payload. Mattermost Advisory ID: MMSA-2026-00610
CVE-2026-21386 1 Mattermost 1 Mattermost Server 2026-06-17 N/A 4.3 MEDIUM
Mattermost versions 11.3.x <= 11.3.0, 11.2.x <= 11.2.2, 10.11.x <= 10.11.10 fail to use consistent error responses when handling the /mute command which allows an authenticated team member to enumerate private channels they are not authorized to know about via differing error messages for nonexistent versus private channels. Mattermost Advisory ID: MMSA-2026-00588
CVE-2026-20796 1 Mattermost 1 Mattermost Server 2026-06-17 N/A 3.1 LOW
Mattermost versions 10.11.x <= 10.11.9 fail to properly validate channel membership at the time of data retrieval which allows a deactivated user to learn team names they should not have access to via a race condition in the /common_teams API endpoint.. Mattermost Advisory ID: MMSA-2025-00549
CVE-2026-20719 1 Mattermost 1 Mattermost Server 2026-06-17 N/A 4.3 MEDIUM
Mattermost versions 11.4.x <= 11.4.0, 11.3.x <= 11.3.1, 11.2.x <= 11.2.3, 10.11.x <= 10.11.11 fail to prevent rendering of external SVGs on link embeds which allows unauthenticated users to crash the Mattermost webapp and desktop app via creating an issue or PR on GitHub.. Mattermost Advisory ID: MMSA-2026-00595
CVE-2026-1629 1 Mattermost 1 Mattermost Server 2026-06-17 N/A 4.3 MEDIUM
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-2026-00580
CVE-2026-0999 1 Mattermost 1 Mattermost Server 2026-06-17 N/A 5.4 MEDIUM
Mattermost versions 11.1.x <= 11.1.2, 10.11.x <= 10.11.9, 11.2.x <= 11.2.1 fail to properly validate login method restrictions which allows an authenticated user to bypass SSO-only login requirements via userID-based authentication. Mattermost Advisory ID: MMSA-2025-00548
CVE-2026-0998 1 Mattermost 2 Mattermost Server, Zoom 2026-06-17 N/A 4.3 MEDIUM
Mattermost versions 11.1.x <= 11.1.2, 10.11.x <= 10.11.9, 11.2.x <= 11.2.1 and Mattermost Plugin Zoom versions <=1.11.0 fail to validate user identity and post ownership in the {{/api/v1/askPMI}} endpoint which allows unauthorized users to start Zoom meetings as any user and overwrite arbitrary posts via direct API calls with manipulated user IDs and post data.. Mattermost Advisory ID: MMSA-2025-00534
CVE-2026-0997 1 Mattermost 2 Mattermost Server, Zoom 2026-06-17 N/A 4.3 MEDIUM
Mattermost versions 11.1.x <= 11.1.2, 10.11.x <= 10.11.9, 11.2.x <= 11.2.1 and Mattermost Plugin Zoom versions <=1.11.0 fail to validate the authenticated user when processing {{/plugins/zoom/api/v1/channel-preference}}, which allows any logged-in user to change Zoom meeting restrictions for arbitrary channels via crafted API requests.. Mattermost Advisory ID: MMSA-2025-00558
CVE-2025-8402 1 Mattermost 1 Mattermost Server 2026-06-17 N/A 4.9 MEDIUM
Mattermost versions 10.8.x <= 10.8.3, 10.5.x <= 10.5.8, 9.11.x <= 9.11.17, 10.10.x <= 10.10.0, 10.9.x <= 10.9.3 fail to validate import data which allows a system admin to crash the server via the bulk import feature.