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Mattermost — Vulnerabilities & Security Advisories 504

Browse all 504 CVE security advisories affecting Mattermost. AI-powered Chinese analysis, POCs, and references for each vulnerability.

Mattermost is an open-source, self-hosted messaging platform designed primarily for secure team communication and collaboration within enterprise environments. With 382 recorded Common Vulnerabilities and Exposures (CVEs), the software has historically been susceptible to critical security flaws, including remote code execution, cross-site scripting, and privilege escalation vulnerabilities. These issues often stem from improper input validation or insufficient access controls within its web interface and API layers. While the platform emphasizes data sovereignty through self-hosting, its extensive vulnerability history highlights the risks associated with complex, feature-rich applications. Security incidents have occasionally involved unauthorized data access or service disruption, underscoring the necessity for rigorous patch management and configuration hardening. Organizations deploying this solution must prioritize regular updates and continuous monitoring to mitigate the inherent risks associated with its large attack surface and frequent exposure to newly discovered exploits.

Found 472 results / 504 Clear Filters
CVE ID Title CVSS Severity Published
CVE-2026-6850 Crafted message attachment causes client-side denial of service via markdown parser regex backtracking in Mattermost — Mattermost CWE-1333 6.5 Medium 2026-07-13
CVE-2026-10106 Unauthorized users can trigger interactive post actions in private channels via action cookie channel mismatch in Mattermost — Mattermost CWE-863 6.5 Medium 2026-07-13
CVE-2026-10085 Ordinary group/direct message member can enable group_constrained and remove all channel participants — Mattermost CWE-862 5.4 Medium 2026-07-13
CVE-2026-9708 Incoming webhook user attribution via unvalidated webhook owner — Mattermost CWE-639 4.9 Medium 2026-07-13
CVE-2026-10103 Authenticated remote cluster can modify or delete posts it does not own in Mattermost Connected Workspaces shared channels — Mattermost CWE-639 4.3 Medium 2026-07-13
CVE-2026-9571 Deactivated user accounts can continue to obtain valid OAuth access tokens via refresh token grant in Mattermost — Mattermost CWE-305 5.9 Medium 2026-07-13
CVE-2026-4339 SSRF via unvalidated attachment URLs in Mattermost Agents plugin MCP server — Mattermost CWE-918 6.5 Medium 2026-06-26
CVE-2026-9699 Mattermost Agents plugin logs unsanitized OpenAI API keys on authentication errors — Mattermost CWE-532 6.8 Medium 2026-06-26
CVE-2026-3472 Markdown image rendering bypass in AI bot tool result posts in Mattermost — Mattermost CWE-693 3.5 Low 2026-06-26
CVE-2026-8823 User Manager can demote bot accounts to guest without bot-management permission — Mattermost CWE-863 3.8 Low 2026-06-22
CVE-2026-6062 IDOR in Jira plugin subscription edit endpoint — Mattermost CWE-639 6.4 Medium 2026-06-22
CVE-2026-6673 Mattermost Jira plugin had unauthenticated {{/ac/installed}} lifecycle callback during pending Jira Cloud install — Mattermost CWE-306 6.4 Medium 2026-06-22
CVE-2026-8074 Improper Permission Check Allows User Manager to Deactivate Bot Accounts — Mattermost CWE-863 3.8 Low 2026-06-22
CVE-2026-9162 Global session revocation does not invalidate active WebSocket connections — Mattermost CWE-613 4.3 Medium 2026-06-22
CVE-2026-5139 GitLab Plugin Allows Non-Admin Users to Modify Default Instance Configuration — Mattermost CWE-862 5.4 Medium 2026-06-22
CVE-2026-8683 Overly long URLs crash the Mattermost Desktop App — Mattermost CWE-770 6.5 Medium 2026-06-15
CVE-2026-6517 Mattermost Desktop App fails to restrict the allow list of domains which NTLM credentials are passed — Mattermost CWE-522 6.3 Medium 2026-06-15
CVE-2026-6961 CVE-2026-6961: Path traversal via unsanitized FileInfo.Name in Mattermost federation sync — Mattermost CWE-22 7.6 High 2026-06-12
CVE-2026-7387 Mattermost group syncable endpoints allow privilege escalation via scheme_admin — Mattermost CWE-863 8.8 High 2026-06-12
CVE-2026-6046 Plugin bot username conflict allows user account to be used as bot identity in Mattermost Server — Mattermost CWE-200 5.3 Medium 2026-06-12
CVE-2026-6689 *Missing* {{invite_user}} *permission check on team creation allows unprivileged users to set open-invite and allowed-domains team settings* — Mattermost CWE-862 4.3 Medium 2026-06-12
CVE-2026-7184 Mattermost Remote Cluster PATCH API Leaks Authentication Tokens — Mattermost CWE-201 6.5 Medium 2026-06-12
CVE-2026-6739 Mattermost: Delegated admins could patch protected default system roles — Mattermost CWE-863 6.7 Medium 2026-06-12
CVE-2026-3433 Mattermost fails to scope role_updated websocket events to authorized team and channel members — Mattermost CWE-200 4.3 Medium 2026-06-12
CVE-2026-6957 Path traversal in Mattermost Legal Hold plugin via unsanitized file name from federated peer allows arbitrary file write. — Mattermost CWE-22 8.0 High 2026-05-27
CVE-2026-4915 Server panic via outgoing webhook responses — Mattermost CWE-754 6.5 Medium 2026-05-25
CVE-2026-28735 GitHub OAuth Scope Validation — Mattermost CWE-863 5.4 Medium 2026-05-22
CVE-2026-4635 Persistent notification timing attack causing server denial of service — Mattermost CWE-362 6.5 Medium 2026-05-22
CVE-2026-3473 Improper file ownership validation in the Boards API allows unauthorised file access — Mattermost CWE-639 5.9 Medium 2026-05-22
CVE-2026-4646 Insufficient input validation in GitHub plugin API causes denial of service — Mattermost CWE-1287 4.3 Medium 2026-05-22

This page lists every published CVE security advisory associated with Mattermost. Each entry links to a detailed page with CVSS scoring, CWE classification, affected products and references. AI-generated Chinese analysis is provided for fast triage.