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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-2026-3636 Sanitize team member data returned by API — Mattermost CWE-200 4.3 Medium 2026-05-22
CVE-2026-5740 Unauthenticated WebSocket binary frame causes denial of service in Mattermost Server — Mattermost CWE-789 7.5 High 2026-05-22
CVE-2026-5308 Missing request body size limits on Zoom plugin HTTP endpoints — Mattermost CWE-400 4.9 Medium 2026-05-22
CVE-2026-5755 Denial of service via crafted TIFF file upload — Mattermost CWE-400 6.5 Medium 2026-05-22
CVE-2026-22880 Mobile SSO authentication flow allows credential theft via malicious server — Mattermost CWE-352 6.1 Medium 2026-05-21
CVE-2026-4858 Path traversal in integration action URL leading to arbitrary API execution via system admin’s auth token. — Mattermost CWE-22 8.0 High 2026-05-21
CVE-2026-4055 Insufficient permission validation on cross-team playbook run creation — Mattermost CWE-863 4.3 Medium 2026-05-21
CVE-2026-3471 Opening a window with {{javascript:alert()}} as URL causes crash in the Mattermost Desktop App — Mattermost CWE-939 6.5 Medium 2026-05-18
CVE-2026-4643 Calling window.close() from server-side content causes crash in the Mattermost Desktop App — Mattermost CWE-754 3.5 Low 2026-05-18
CVE-2026-6333 SSRF via Host Header Spoofing in Custom Slash Commands — Mattermost CWE-918 3.5 Low 2026-05-18
CVE-2026-6345 Prevent password disclosure and force reset during Slack import — Mattermost CWE-522 6.5 Medium 2026-05-18
CVE-2026-6346 Sensitive credentials exposed in plaintext in Mattermost support packets — Mattermost CWE-200 8.7 High 2026-05-18
CVE-2026-28732 Slash command trigger-word update allowed command hijacking — Mattermost CWE-863 4.3 Medium 2026-05-18
CVE-2026-6343 Mattermost Playbooks Plugin fails to enforce view permissions in list endpoints, allowing unauthorized access to public playbooks — Mattermost CWE-863 4.3 Medium 2026-05-18
CVE-2026-6347 Mattermost Calls plugin exposes TURN server credentials in plaintext in support packets — Mattermost CWE-200 7.6 High 2026-05-18
CVE-2026-5163 Missing authorization check in AI message rewrite endpoint allows access to private thread content — Mattermost CWE-862 6.5 Medium 2026-05-18
CVE-2026-3117 Instance and webhook GitLab plugin commands were able to be run by non-admin users — Mattermost CWE-862 6.5 Medium 2026-05-18
CVE-2026-4286 Playbooks Plugin fails to validate team transfers, allowing unauthorized removal of member access via playbook update — Mattermost CWE-863 3.1 Low 2026-05-18
CVE-2026-6339 Missing request origin validation on burn-on-read reveal endpoint — Mattermost CWE-346 4.3 Medium 2026-05-18
CVE-2026-6340 Memory Exhaustion via Malicious 7zip File Upload — Mattermost CWE-789 4.3 Medium 2026-05-18
CVE-2026-6341 Incomplete group locking implementation — Mattermost CWE-863 4.3 Medium 2026-05-18
CVE-2026-6342 Group prefix matching bypass for subscriptions — Mattermost CWE-863 4.3 Medium 2026-05-18
CVE-2026-3495 Unescaped variables during error page composition — Mattermost CWE-79 3.8 Low 2026-05-18
CVE-2026-4273 Insufficient token rotation validation in remote cluster invite confirmation — Mattermost CWE-863 3.7 Low 2026-05-18
CVE-2026-3637 Mattermost fails to enforce create_post permission when editing posts — Mattermost CWE-862 4.3 Medium 2026-05-18
CVE-2026-2325 Improper Input Validation in MS Teams Meetings API Handler — Mattermost CWE-770 4.3 Medium 2026-05-18
CVE-2026-28759 Insufficient authorization in shared channel membership sync allows remote cluster to remove users from arbitrary channels — Mattermost CWE-863 4.3 Medium 2026-05-18
CVE-2026-6334 OAuth authorization code client binding not enforced during token redemption in Mattermost — Mattermost CWE-305 3.1 Low 2026-05-18
CVE-2026-4053 post edit time limit is not enforced on some post update operations — Mattermost CWE-672 3.1 Low 2026-05-15
CVE-2026-4054 SVG content served through Mattermost image proxy despite Content-Type restrictions causes client-side denial of service — Mattermost CWE-754 4.3 Medium 2026-05-15

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.