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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.

CVE ID Title CVSS Severity Published
CVE-2026-5132 Unbounded zlib decompression in Calls SDP WebSocket messages — Mattermost CWE-409 6.5 Medium 2026-09-14
CVE-2026-15814 Uploading a crafted image causes excessive memory allocation in the Mattermost Server — Mattermost CWE-409 6.5 Medium 2026-09-14
CVE-2026-10542 Playbooks channel action update validation issue — Mattermost CWE-639 5.0 Medium 2026-09-14
CVE-2026-14344 Inconsistent authorization checks in Mattermost Boards endpoints — Mattermost CWE-862 4.3 Medium 2026-09-14
CVE-2026-12882 Mattermost Markdown autolink parsing denial of service — Mattermost CWE-407 4.3 Medium 2026-09-14
CVE-2026-11993 Fix authenticated members disabling file content indexing server-wide via extraction pool exhaustion — Mattermost CWE-770 4.3 Medium 2026-09-14
CVE-2026-14259 Board archive import bypasses team board creation permissions — Mattermost CWE-862 4.3 Medium 2026-09-14
CVE-2026-75587 Plaintext pre-auth secret exposure via Desktop App diagnostics report — Mattermost CWE-200 3.6 Low 2026-08-17
CVE-2026-9693 Mattermost thread memberships persist after team removal, exposing private channel thread metadata on re-invite — Mattermost CWE-459 3.5 Low 2026-08-17
CVE-2026-9859 Mattermost Boards plugin didn’t enforce role-based authorization on board channel link allowing board editors to expose boards to arbitrary channels — Mattermost CWE-863 6.5 Medium 2026-08-17
CVE-2026-9816 Insufficient server-side validation of board member role fields permits privilege escalation — Mattermost CWE-863 8.3 High 2026-08-17
CVE-2026-10080 Boards plugin panics on WebSocket command with non-string field types — Mattermost CWE-704 6.5 Medium 2026-08-17
CVE-2026-10527 Boards plugin retains Board Admin rights for users demoted to System Guest — Mattermost CWE-863 6.3 Medium 2026-08-17
CVE-2026-15754 Missing per-channel team-scope check in ABAC access control policy unassign allows cross-team policy removal — Mattermost CWE-863 4.2 Medium 2026-08-17
CVE-2026-16044 Insufficient validation of guest board admin privileges on archive import — Mattermost CWE-863 3.9 Medium 2026-08-17
CVE-2026-16045 Delegated OAuth tokens could revoke unrelated OAuth application authorizations — Mattermost CWE-863 2.7 Medium 2026-08-17
CVE-2026-16049 _GitLab Plugin allows cross-channel post injection and phishing via missing channel permission checks in issue API endpoints_ — Mattermost CWE-862 3.9 Medium 2026-08-17
CVE-2026-16047 Board channel linking without read channel permission validation — Mattermost CWE-862 4.3 Medium 2026-08-17
CVE-2026-16046 Missing run-state validation on finished playbook runs — Mattermost CWE-863 3.5 Medium 2026-08-17
CVE-2026-16048 Channel member roles accept out-of-scope roles — Mattermost CWE-863 6.3 Medium 2026-08-17
CVE-2026-14298 Boards archive import endpoint allows resource exhaustion via zip bomb and file size limit bypass in Mattermost — Mattermost CWE-409 6.5 Medium 2026-08-13
CVE-2026-7521 SAML certificate deletion allows path traversal to delete arbitrary files outside the config directory — Mattermost CWE-22 5.5 Medium 2026-07-28
CVE-2026-10819 Mattermost Server Denial of Service via Animated GIF Emoji Upload — Mattermost CWE-409 6.5 Medium 2026-07-27
CVE-2026-10600 Denial of service via unbounded document content extraction in Mattermost Server — Mattermost CWE-770 4.3 Medium 2026-07-27
CVE-2026-8075 Posting a malicious markdown image crashes the Mattermost Desktop App — Mattermost CWE-754 6.5 Medium 2026-07-17
CVE-2026-9602 Mattermost Desktop App crashes when malformed arguments are provided to some exposed IPC methods — Mattermost CWE-400 5.7 Medium 2026-07-17
CVE-2026-6541 Unscoped updates to other playbooks' metric configuration — Mattermost CWE-639 4.3 Medium 2026-07-13
CVE-2026-9820 Mattermost schemes teams endpoint exposes private team invite IDs — Mattermost CWE-862 3.8 Low 2026-07-13
CVE-2026-9824 Remote cluster metadata enumeration via /share-channel autocomplete — Mattermost CWE-862 4.3 Medium 2026-07-13
CVE-2026-9597 Deactivated guest accounts can authenticate via magic-link token in Mattermost REST API login endpoint — Mattermost CWE-305 5.4 Medium 2026-07-13

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.