{"id":"CVE-2021-21241","aliases":["GHSA-hh7m-rx4f-4vpv","PYSEC-2021-91"],"url":"https://o3.security/vulnerability/CVE-2021-21241","summary":"CSRF can expose users authentication token","details":"The Python \"Flask-Security-Too\" package is used for adding security features to your Flask application. It is an is a independently maintained version of Flask-Security based on the 3.0.0 version of Flask-Security. In Flask-Security-Too from version 3.3.0 and before version 3.4.5, the /login and /change endpoints can return the authenticated user's authentication token in response to a GET request. Since GET requests aren't protected with a CSRF token, this could lead to a malicious 3rd party site acquiring the authentication token. Version 3.4.5 and version 4.0.0 are patched. As a workaround, if you aren't using authentication tokens - you can set the SECURITY_TOKEN_MAX_AGE to \"0\" (seconds) which should make the token unusable.","published":"2021-01-11T21:15:13.377Z","modified":"2026-03-15T22:38:58.440232Z","cvss":{"score":7.4,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:N/A:N"},"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[{"ecosystem":"PyPI","name":"flask-security-too","fixedVersion":"3.4.5"}],"fix":{"url":"https://github.com/Flask-Middleware/flask-security/commit/61d313150b5f620d0b800896c4f2199005e84b1f","label":"Flask-Middleware/flask-security@61d3131"},"references":[{"type":"ADVISORY","url":"https://github.com/Flask-Middleware/flask-security/releases/tag/3.4.5"},{"type":"ADVISORY","url":"https://github.com/Flask-Middleware/flask-security/security/advisories/GHSA-hh7m-rx4f-4vpv"},{"type":"FIX","url":"https://github.com/Flask-Middleware/flask-security/commit/61d313150b5f620d0b800896c4f2199005e84b1f"},{"type":"FIX","url":"https://github.com/Flask-Middleware/flask-security/commit/6d50ee9169acf813257c37b75babe9c28e83542a"},{"type":"FIX","url":"https://github.com/Flask-Middleware/flask-security/pull/422"},{"type":"PACKAGE","url":"https://pypi.org/project/Flask-Security-Too"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-03-15T22:38:58.440232Z"}}