{"id":"CVE-2026-19867","url":"https://www.cyber-defence.io/tools/cve/CVE-2026-19867","generatedAt":"2026-10-28T08:11:00.493Z","title":"Mattermost versions 11.10.x <= 11.10.0, 11.9.x <= 11.9.1, 11.8.x <= 11.8.5, 11.7.x <= 11.7.10 fail to cap the number and size of mention keys stored in a user's notification properties, and to bound the quadratic multibyte-keyword matching performed for…","description":"Mattermost versions 11.10.x <= 11.10.0, 11.9.x <= 11.9.1, 11.8.x <= 11.8.5, 11.7.x <= 11.7.10 fail to cap the number and size of mention keys stored in a user's notification properties, and to bound the quadratic multibyte-keyword matching performed for each post, which allows an authenticated user to degrade post-processing latency and consume excessive CPU on behalf of other members of any channel they share via storing an oversized notify_props.mention_keys list on their own profile.. Mattermost Advisory ID: MMSA-2026-00773","published":"2026-10-16T07:17:13.000Z","lastModified":"2026-10-16T19:23:19.000Z","status":"Awaiting Analysis","sourceIdentifier":"responsibledisclosure@mattermost.com","cvss":{"version":"3.1","score":4.3,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L"},"cwe":["CWE-770"],"affected":[],"epss":{"score":0.00212,"percentile":0.11417,"date":"2026-10-27","history":[{"date":"2026-10-16","score":0.00212,"percentile":0.10758}]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"low","text":"Lower severity and a low EPSS score (0.21%). Track it; it rarely justifies an emergency change on its own."},"changes":[{"kind":"new","label":"New CVE","at":"2026-10-16T07:17:13.000Z","detail":{"score":"4.3","severity":"MEDIUM","publishedAt":"2026-10-16T07:17:13.353Z"},"summary":"New CVE, medium severity (CVSS 4.3)."}],"references":[{"url":"https://mattermost.com/security-updates","source":"responsibledisclosure@mattermost.com"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-19867","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}