CVE-2021-23401

Advisory

This affects all versions of package Flask-User. When using the make_safe_url function, 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 or \\\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.

Affected package

Affected versions

Fixed versions

Vulnerability changelog

This affects all versions of package Flask-User. When using the make_safe_url function, 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 or \\\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. See CVE-2021-23401.


MISC:https://github.com/lingthio/Flask-User: https://github.com/lingthio/Flask-User
MISC:https://github.com/lingthio/Flask-User/blob/master/flask_user/user_manager__utils.py: https://github.com/lingthio/Flask-User/blob/master/flask_user/user_manager__utils.py
MISC:https://snyk.io/vuln/SNYK-PYTHON-FLASKUSER-1293188: https://snyk.io/vuln/SNYK-PYTHON-FLASKUSER-1293188

Resources

• https://github.com/lingthio/Flask-User
• https://github.com/lingthio/Flask-User/blob/master/flask_user/user_manager__utils.py
• https://snyk.io/vuln/SNYK-PYTHON-FLASKUSER-1293188
• https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-23401