{"id":"CVE-2026-95666","title":"Mattermost versions 11.9.x <= 11.9.1, 11.8.x <= 11.8.5, 11.7.x <= 11.7.10, 11.10.x <= 11.10.1 fail to limit the length of the post ID array accepted by the bulk reactions endpoint which allows an authenticated user to cause excessive dat…","summary":"Mattermost versions 11.9.x <= 11.9.1, 11.8.x <= 11.8.5, 11.7.x <= 11.7.10, 11.10.x <= 11.10.1 fail to limit the length of the post ID array accepted by the bulk reactions endpoint which allows an authenticated user to cause excessive dat…","severity":"medium","cvss":4.3,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L","cwe":["CWE-770"],"vendor":"mattermost","product":"mattermost_server","affected":["mattermost_server >= 11.7.0, < 11.7.11","mattermost_server >= 11.8.0, < 11.8.6","mattermost_server >= 11.9.0, < 11.9.2","mattermost_server >= 11.10.0, < 11.10.2"],"patched":["mattermost_server 11.10.2"],"published":"2026-09-22","updated":"2026-10-07","sourceUpdated":"2026-10-07T16:48:51.163","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-95666","references":[{"url":"https://mattermost.com/security-updates","label":"responsibledisclosure@mattermost.com"}],"tags":["nvd","cve.org"],"epss":0.00367,"epssPercentile":0.30401,"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"partial","timestamp":"2026-09-22T13:55:15.216071Z"},"ingestedAt":"2026-09-22T14:04:19.584Z","slug":"CVE-2026-95666","body":"## Overview\n\nMattermost versions 11.9.x <= 11.9.1, 11.8.x <= 11.8.5, 11.7.x <= 11.7.10, 11.10.x <= 11.10.1 fail to limit the length of the post ID array accepted by the bulk reactions endpoint which allows an authenticated user to cause excessive database load via a crafted request to {{POST /api/v4/posts/ids/reactions}}.. Mattermost Advisory ID: MMSA-2026-00771\n\n## Affected\n\n- `mattermost_server >= 11.7.0, < 11.7.11`\n- `mattermost_server >= 11.8.0, < 11.8.6`\n- `mattermost_server >= 11.9.0, < 11.9.2`\n- `mattermost_server >= 11.10.0, < 11.10.2`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `mattermost_server 11.10.2`","depth":"sunlit","depthScore":24,"depthScoreParts":{"impact":23.7,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}