{"cve":"CVE-2025-53021","nvd":{"published":"2025-06-24T20:15:26.867","modified":"2026-06-17T09:37:29.393","status":"Analyzed","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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N","score":4.2},"cwes":["CWE-384"],"references":["https://github.com/moodle/moodle/releases/tag/v3.11.18","https://moodledev.io/general/releases#moodle-311","https://rentry.co/moodle-oauth2-cve"],"products":["moodle:moodle"],"source":"nvd","synced_at":"2026-10-19T22:03:23.287444849+00:00"},"epss":{"cve":"CVE-2025-53021","score":0.0037,"percentile":0.30885,"date":"2026-11-01"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}