{"id":"CVE-2021-23385","aliases":["GHSA-cg8c-gc2j-2wf7","PYSEC-2026-809"],"url":"https://o3.security/vulnerability/CVE-2021-23385","summary":"Flask-Security vulnerable to Open Redirect","details":"This affects all versions of package Flask-Security. When using the get_post_logout_redirect and get_post_login_redirect functions, it is possible to bypass URL validation and redirect a user to an arbitrary URL by providing multiple back slashes such as \\\\\\evil.com/path. This vulnerability is only exploitable if an alternative WSGI server other than Werkzeug is used, or the default behaviour of Werkzeug is modified using 'autocorrect_location_header=False. **Note:** Flask-Security is not maintained anymore.","published":"2022-08-02T14:15:10.017Z","modified":"2026-07-07T11:56:49.533724357Z","cvss":{"score":6.1,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N"},"epss":{"score":0.0113,"percentile":0.63213,"asOf":"2026-07-31"},"cisaKev":null,"exploitsKnown":1,"affectedPackages":[{"ecosystem":"PyPI","name":"flask-security","fixedVersion":null}],"fix":null,"references":[{"type":"WEB","url":"https://lists.debian.org/debian-lts-announce/2023/08/msg00034.html"},{"type":"ADVISORY","url":"https://snyk.io/blog/url-confusion-vulnerabilities/"},{"type":"PACKAGE","url":"https://github.com/mattupstate/flask-security"},{"type":"EVIDENCE","url":"https://security.snyk.io/vuln/SNYK-PYTHON-FLASKSECURITY-1293234"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-07-07T11:56:49.533724357Z"}}