CVE-2021-23393

Advisory

This affects the package Flask-Unchained before 0.9.0. When using the the _validate_redirect_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. 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 the package Flask-Unchained before 0.9.0. When using the the _validate_redirect_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. 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-2021-23393.


MISC:https://github.com/briancappello/flask-unchained/commit/71e36b28166f9ffbe0a991f51127f0984f7e6a40: https://github.com/briancappello/flask-unchained/commit/71e36b28166f9ffbe0a991f51127f0984f7e6a40
MISC:https://snyk.io/vuln/SNYK-PYTHON-FLASKUNCHAINED-1293189: https://snyk.io/vuln/SNYK-PYTHON-FLASKUNCHAINED-1293189

Resources

• https://github.com/briancappello/flask-unchained/commit/71e36b28166f9ffbe0a991f51127f0984f7e6a40
• https://snyk.io/vuln/SNYK-PYTHON-FLASKUNCHAINED-1293189
• https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-23393