{"identifier":"CVE-2026-93851","cve":{"id":"CVE-2026-93851","description":"Mattermost versions 11.9.x <= 11.9.1, 11.8.x <= 11.8.5, 11.7.x <= 11.7.10 fail to validate the target post ID in the Agents plugin's mention reminder component, which allows an authenticated user who can post in a channel visible to a system administrator to cause the administrator's browser to send an unintended API request, resulting in replacement of an installed plugin and code execution on the server, via a crafted post containing a forged mention reminder that the administrator clicks. Mattermost Advisory ID: MMSA-2026-00742","published":"2026-10-28T22:17:17.310000+00:00","modified":"2026-10-29T16:20:06.207000+00:00","status":"Awaiting Analysis","score":8.0,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:H","cvss_version":"3.1","affected":[],"weaknesses":["CWE-22"],"references":[{"url":"https://mattermost.com/security-updates","source":"responsibledisclosure@mattermost.com"}],"kev":null,"kev_checked":true,"metrics":{"cvssMetricV31":[{"source":"responsibledisclosure@mattermost.com","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:H","baseScore":8.0,"baseSeverity":"HIGH","attackVector":"NETWORK","attackComplexity":"HIGH","privilegesRequired":"LOW","userInteraction":"REQUIRED","scope":"CHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"},"exploitabilityScore":1.3,"impactScore":6.0}],"ssvcV203":[{"source":"134c704f-9b21-4f2e-91b3-4a467353bcc0","ssvcData":{"timestamp":"2026-10-29T15:14:58.910496Z","id":"CVE-2026-93851","options":[{"exploitation":"none"},{"automatable":"no"},{"technicalImpact":"total"}],"role":"CISA Coordinator","version":"2.0.3"}}]},"configurations":[],"source":"nvd","retrieved_at":"2026-10-29T19:36:39.492735+00:00","exploited":false,"kev_stale":false,"products":[],"priority":{"label":"Assess exposure and vendor guidance","reasons":["No higher-priority signal is available in the current stored evidence."]},"epss":{"probability":0.00266,"percentile":0.1878,"date":"2026-10-29","stale":false},"version_assessment":null},"news":[],"campaigns":[],"domains":[{"domain":"mattermost.com","source_url":"https://mattermost.com/security-updates","investigate_url":"https://investigate.aeglixmind.com/#mattermost.com"}],"arsenal_url":"https://arsenal.aeglixmind.com/?cve=CVE-2026-93851","catalog_url":"https://cves.aeglixmind.com/cve/CVE-2026-93851","research_url":"https://investigate.aeglixmind.com/research/cve/CVE-2026-93851","coverage":{"news_candidates_checked":0,"campaign_candidates_checked":0,"bounded":false,"notice":"Exact CVE mentions in stored public excerpts and reviewed campaign content only. A mention is not proof of exploitation, attribution or tool suitability. Missing matches do not establish absence."}}