{"id":"CVE-2026-12985","title":"Mattermost versions 11.9.x <= 11.9.0, 11.8.x <= 11.8.4, 11.7.x <= 11.7.7 Mattermost failed to validate Dynamic Client Registration redirect URIs by URL component (matching glob patterns against the raw URI string instead) which allows a …","summary":"Mattermost versions 11.9.x <= 11.9.0, 11.8.x <= 11.8.4, 11.7.x <= 11.7.7 Mattermost failed to validate Dynamic Client Registration redirect URIs by URL component (matching glob patterns against the raw URI string instead) which allows a …","severity":"medium","cvss":6.8,"cvssVector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N","cwe":["CWE-601"],"vendor":"mattermost","product":"mattermost_server","affected":["mattermost_server >= 11.7.0, < 11.7.8","mattermost_server >= 11.8.0, < 11.8.5","mattermost_server >= 11.9.0, < 11.9.1"],"patched":["mattermost_server 11.9.1"],"published":"2026-09-14","updated":"2026-10-07","sourceUpdated":"2026-10-07T17:58:56.437","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-12985","references":[{"url":"https://mattermost.com/security-updates","label":"responsibledisclosure@mattermost.com"}],"tags":["nvd","cve.org"],"epss":0.00268,"epssPercentile":0.18802,"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"total","timestamp":"2026-09-14T19:12:54.322562Z"},"ingestedAt":"2026-09-14T15:23:07.423Z","slug":"CVE-2026-12985","body":"## Overview\n\nMattermost versions 11.9.x <= 11.9.0, 11.8.x <= 11.8.4, 11.7.x <= 11.7.7 Mattermost failed to validate Dynamic Client Registration redirect URIs by URL component (matching glob patterns against the raw URI string instead) which allows a remote unauthenticated attacker to register an OAuth client with an attacker-controlled callback host that bypasses the configured redirect URI allowlist via a crafted redirect URI that places an allowlisted host/path suffix inside the query string.. Mattermost Advisory ID: MMSA-2026-00700\n\n## Affected\n\n- `mattermost_server >= 11.7.0, < 11.7.8`\n- `mattermost_server >= 11.8.0, < 11.8.5`\n- `mattermost_server >= 11.9.0, < 11.9.1`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `mattermost_server 11.9.1`","depth":"sunlit","depthScore":37,"depthScoreParts":{"impact":37.4,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}