{"id":"CVE-2025-53021","url":"https://www.cyber-defence.io/tools/cve/CVE-2025-53021","generatedAt":"2026-10-28T00:27:44.928Z","title":"A session fixation vulnerability in Moodle 3.x through 3.11.18 allows unauthenticated attackers to hijack user sessions via the sesskey parameter.","description":"A session fixation vulnerability in Moodle 3.x through 3.11.18 allows unauthenticated attackers to hijack user sessions via the sesskey parameter. The sesskey can be obtained without authentication and reused within the OAuth2 login flow, resulting in the victim's session being linked to the attacker's. Successful exploitation results in full account takeover. According to the Moodle Releases page, \"Bug fixes for security issues in 3.11.x ended 11 December 2023.\" NOTE: This vulnerability only affects products that are no longer supported by the maintainer.","published":"2025-06-24T20:15:27.000Z","lastModified":"2026-06-17T09:37:29.000Z","status":"Analyzed","sourceIdentifier":"cve@mitre.org","cvss":{"version":"3.1","score":4.2,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N"},"cwe":["CWE-384"],"affected":["moodle/moodle"],"epss":{"score":0.00325,"percentile":0.25333,"date":"2026-10-26","history":[]},"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 (0.33%). Track it; it rarely justifies an emergency change on its own."},"changes":[],"references":[{"url":"https://github.com/moodle/moodle/releases/tag/v3.11.18","tags":["Product"],"source":"cve@mitre.org"},{"url":"https://moodledev.io/general/releases#moodle-311","tags":["Product"],"source":"cve@mitre.org"},{"url":"https://rentry.co/moodle-oauth2-cve","tags":["Third Party Advisory"],"source":"cve@mitre.org"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2025-53021","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."}