# Mattermost Server vulnerabilities Source: https://junglewise.ai/threats/technologies/server-public Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats Updated: 12 November 2026, 00:07 UTC. Rebuilt every hour. Data: https://junglewise.ai/threats/technologies/server-public.json License: CC BY 4.0 with a link back Junglewise Threat Intelligence has tracked 111 vulnerabilities in Mattermost Server: 0 in the last 7 days and 34 in the last 90 days, 2 of them critical and 0 exploited in the wild. The most recent, CVE-2026-93851, was published on 28 October 2026. 18 vulnerabilities in the last four weeks, up 20% on the four before (15). ## Counts - Last 7 days: 0 - Last 30 days: 18 - Last 90 days: 34 - All time: 111 (2 critical, 0 exploited in the wild) ## About Mattermost Server Server Public is a library containing shared components and utilities for the Mattermost server. ## Latest Mattermost Server vulnerabilities - [CVE-2026-93851: Mattermost CSRF via Agents plugin mention reminder validation](https://junglewise.ai/threats/cve-2026-93851-mattermost-versions-11-9-x-11-9-1-11-8-x-11-8-5-11-7-x-11-7-10) (high, CVSS 8, published 28 Oct 2026) - [CVE-2026-93850: Mattermost denial of service via PDF text extraction memory exhaustion](https://junglewise.ai/threats/cve-2026-93850-mattermost-versions-11-9-x-11-9-1-11-8-x-11-8-5-11-7-x-11-7-10-11) (medium, CVSS 6.5, published 26 Oct 2026) - [CVE-2026-93849: Mattermost denial of service in WebSocket msgpack decoder](https://junglewise.ai/threats/cve-2026-93849-mattermost-versions-11-9-x-11-9-1-11-8-x-11-8-5-11-7-x-11-7-10-11) (medium, CVSS 6.5, published 26 Oct 2026) - [CVE-2026-19621: Mattermost information disclosure in post deletion events](https://junglewise.ai/threats/cve-2026-19621-mattermost-versions-11-10-x-11-10-0-11-7-x-11-7-9-11-9-x-11-9-1) (medium, CVSS 6.5, published 16 Oct 2026) - [CVE-2026-19600: Mattermost authentication token leak in server logs](https://junglewise.ai/threats/cve-2026-19600-mattermost-versions-11-9-x-11-9-1-11-8-x-11-8-5-11-7-x-11-7-10-11) (medium, CVSS 4.5, published 16 Oct 2026) - [CVE-2026-19076: Mattermost authentication bypass in OAuth account takeover](https://junglewise.ai/threats/cve-2026-19076-mattermost-versions-11-10-x-11-10-0-11-7-x-11-7-9-11-9-x-11-9-1) (medium, CVSS 4.4, published 16 Oct 2026) - [CVE-2026-18799: Mattermost Slack import account binding privilege escalation](https://junglewise.ai/threats/cve-2026-18799-mattermost-versions-11-10-x-11-10-0-11-7-x-11-7-9-11-9-x-11-9-1) (medium, CVSS 4.3, published 16 Oct 2026) - [CVE-2026-18560: Mattermost authorization bypass in post flag status](https://junglewise.ai/threats/cve-2026-18560-mattermost-versions-11-10-x-11-10-0-11-7-x-11-7-9-11-9-x-11-9-1) (medium, CVSS 4.3, published 16 Oct 2026) - [CVE-2026-18256: Mattermost information disclosure in team search](https://junglewise.ai/threats/cve-2026-18256-mattermost-versions-11-10-x-11-10-0-11-7-x-11-7-9-11-9-x-11-9-1) (medium, CVSS 4.3, published 16 Oct 2026) - [CVE-2026-18223: Mattermost email validation bypass in invitation tokens](https://junglewise.ai/threats/cve-2026-18223-mattermost-versions-11-10-x-11-10-0-11-7-x-11-7-9-11-9-x-11-9-1) (medium, CVSS 5, published 16 Oct 2026) - [CVE-2026-16453: Mattermost SAML RelayState integrity verification bypass](https://junglewise.ai/threats/cve-2026-16453-mattermost-versions-11-10-x-11-10-0-11-7-x-11-7-9-11-9-x-11-9-1) (high, CVSS 7.1, published 16 Oct 2026) - [CVE-2026-16251: Mattermost Server memory exhaustion in remote image proxy](https://junglewise.ai/threats/cve-2026-16251-mattermost-versions-11-10-x-11-10-0-11-7-x-11-7-9-11-9-x-11-9-1) (medium, CVSS 6.5, published 16 Oct 2026) - [CVE-2026-19867: Mattermost Server denial of service via oversized mention keys](https://junglewise.ai/threats/cve-2026-19867-mattermost-versions-11-10-x-11-10-0-11-9-x-11-9-1-11-8-x-11-8-5) (medium, CVSS 4.3, published 16 Oct 2026) - [CVE-2026-19603: Mattermost information disclosure in user status API](https://junglewise.ai/threats/cve-2026-19603-mattermost-versions-11-9-x-11-9-1-11-8-x-11-8-5-11-7-x-11-7-10-11) (medium, CVSS 4.3, published 16 Oct 2026) - [CVE-2026-19601: Mattermost AD/LDAP bind password exposure in system configuration](https://junglewise.ai/threats/cve-2026-19601-mattermost-versions-11-9-x-11-9-1-11-8-x-11-8-5-11-7-x-11-7-10-11) (medium, CVSS 4.9, published 16 Oct 2026) - [CVE-2026-19541: Mattermost OAuth connection secret exposure via validation bypass](https://junglewise.ai/threats/cve-2026-19541-mattermost-versions-11-9-x-11-9-1-11-8-x-11-8-5-11-7-x-11-7-10-11) (medium, CVSS 6.5, published 16 Oct 2026) - [CVE-2026-18795: Mattermost authorization bypass in DM/GM post quarantine](https://junglewise.ai/threats/cve-2026-18795-mattermost-versions-11-10-x-11-10-0-11-7-x-11-7-9-11-9-x-11-9-1) (medium, CVSS 6.4, published 16 Oct 2026) - [CVE-2026-18551: Mattermost privilege escalation in guest and admin role validation](https://junglewise.ai/threats/cve-2026-18551-mattermost-versions-11-10-x-11-10-0-11-7-x-11-7-9-11-9-x-11-9-1) (medium, CVSS 6.5, published 16 Oct 2026) - [CVE-2026-96260: Mattermost memory exhaustion in CSRF validation for plugin endpoints](https://junglewise.ai/threats/cve-2026-96260-mattermost-versions-11-9-x-11-9-1-11-8-x-11-8-5-11-7-x-11-7-10-11) (medium, CVSS 6.5, published 22 Sep 2026) - [CVE-2026-96259: Mattermost internal-connection filter bypass in OAuth endpoints](https://junglewise.ai/threats/cve-2026-96259-mattermost-versions-11-9-x-11-9-1-11-8-x-11-8-5-11-7-x-11-7-10-11) (medium, CVSS 5.5, published 22 Sep 2026) - [CVE-2026-95666: Mattermost denial of service via unbounded post ID array](https://junglewise.ai/threats/cve-2026-95666-mattermost-versions-11-9-x-11-9-1-11-8-x-11-8-5-11-7-x-11-7-10-11) (medium, CVSS 4.3, published 22 Sep 2026) - [CVE-2026-91181: Mattermost information disclosure in data retention teams endpoint](https://junglewise.ai/threats/cve-2026-91181-mattermost-information-disclosure-in-data-retention-teams) (medium, CVSS 6.5, published 14 Sep 2026) - [CVE-2026-12985: Mattermost OAuth redirect URI validation bypass](https://junglewise.ai/threats/cve-2026-12985-mattermost-oauth-redirect-uri-validation-bypass) (medium, CVSS 6.8, published 14 Sep 2026) - [CVE-2026-86349: Mattermost Markdown parser denial of service](https://junglewise.ai/threats/cve-2026-86349-mattermost-markdown-parser-denial-of-service) (medium, CVSS 4.3, published 14 Sep 2026) - [CVE-2026-86348: Mattermost denial of service via handler panic in post-action request](https://junglewise.ai/threats/cve-2026-86348-mattermost-denial-of-service-via-handler-panic-in-post-action) (medium, CVSS 4.3, published 14 Sep 2026) ## Most severe Mattermost Server vulnerabilities - [CVE-2025-12421: GO-2025-4170 - Mattermost fails to to verify the token used during code exchange in github.com/mattermost/mattermost-server](https://junglewise.ai/threats/cve-2025-12421-mattermost-fails-to-to-verify-the-token-used-during-code-exchange) (critical, CVSS 9.9, published 27 Nov 2025) - [CVE-2025-12419: Mattermost fails to properly validate OAuth state tokens during OpenID Connect authentication](https://junglewise.ai/threats/cve-2025-12419-mattermost-fails-to-properly-validate-oauth-state-tokens-during) (critical, CVSS 9.9, published 27 Nov 2025) - [CVE-2026-7387: Mattermost privilege escalation in group syncable link and patch endpoints](https://junglewise.ai/threats/cve-2026-7387-mattermost-privilege-escalation-in-group-syncable-link-and-patch) (high, CVSS 8.8, published 12 Jun 2026) - [CVE-2026-6346: Mattermost sensitive information disclosure in support packet generation](https://junglewise.ai/threats/cve-2026-6346-mattermost-sensitive-information-disclosure-in-support-packet) (high, CVSS 8.7, published 18 May 2026) - [CVE-2026-4858: Mattermost path traversal in integration action URL](https://junglewise.ai/threats/cve-2026-4858-mattermost-path-traversal-in-integration-action-url) (high, CVSS 8, published 21 May 2026) - [CVE-2026-93851: Mattermost CSRF via Agents plugin mention reminder validation](https://junglewise.ai/threats/cve-2026-93851-mattermost-versions-11-9-x-11-9-1-11-8-x-11-8-5-11-7-x-11-7-10) (high, CVSS 8, published 28 Oct 2026) - [CVE-2026-6961: Mattermost path traversal in shared channel file sync](https://junglewise.ai/threats/cve-2026-6961-mattermost-path-traversal-in-shared-channel-file-sync) (high, CVSS 7.6, published 12 Jun 2026) - [CVE-2026-6347: Mattermost Calls plugin information disclosure in support packets](https://junglewise.ai/threats/cve-2026-6347-mattermost-calls-plugin-information-disclosure-in-support-packets) (high, CVSS 7.6, published 18 May 2026) - [CVE-2026-5740: Mattermost Server denial of service via msgpack WebSocket frames](https://junglewise.ai/threats/cve-2026-5740-mattermost-server-denial-of-service-via-msgpack-websocket-frames) (high, CVSS 7.5, published 22 May 2026) - [CVE-2026-5308: Mattermost denial of service in plugin HTTP endpoints](https://junglewise.ai/threats/cve-2026-5308-mattermost-denial-of-service-in-plugin-http-endpoints) (high, CVSS 7.5, published 22 May 2026) ## Vulnerabilities per week 18 vulnerabilities in the last four weeks, up 20% on the four before (15). | Week of | Vulns | Critical | Exploited | | --- | --- | --- | --- | | 17 Aug 2026 | 1 | 0 | 0 | | 24 Aug 2026 | 0 | 0 | 0 | | 31 Aug 2026 | 0 | 0 | 0 | | 7 Sep 2026 | 0 | 0 | 0 | | 14 Sep 2026 | 12 | 0 | 0 | | 21 Sep 2026 | 3 | 0 | 0 | | 28 Sep 2026 | 0 | 0 | 0 | | 5 Oct 2026 | 0 | 0 | 0 | | 12 Oct 2026 | 15 | 0 | 0 | | 19 Oct 2026 | 0 | 0 | 0 | | 26 Oct 2026 | 3 | 0 | 0 | | 2 Nov 2026 | 0 | 0 | 0 | | 9 Nov 2026 | 0 | 0 | 0 | ## Other Mattermost technologies - [Mattermost Desktop App](https://junglewise.ai/threats/technologies/desktop-app): 14 vulnerabilities - [Mattermost](https://junglewise.ai/threats/technologies/mattermost): 9 vulnerabilities - [Mattermost Plugins](https://junglewise.ai/threats/technologies/mattermost-plugins): 5 vulnerabilities - [Mattermost GitHub Plugin for Mattermost](https://junglewise.ai/threats/technologies/github-plugin): 3 vulnerabilities ## Sources NVD, GitHub Security Advisories, OSV, the CISA Known Exploited Vulnerabilities catalog, FIRST EPSS and vendor advisories. Rebuilt every hour. Cite as: Junglewise Threat Intelligence, "Mattermost Server vulnerabilities", https://junglewise.ai/threats/technologies/server-public, 12 November 2026.