CVE-2021-23385

MediumCVSS 6.1/10Last modified Jun 17, 2026

Description

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.

Metrics

CVSS 3.1 6.1/10CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Weakness enumeration

CWE-601

Affected software

Vendor	Product	Versions
n/a	Flask-Security	< unspecified

References

https://github.com/mattupstate/flask-securityProduct, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2023/08/msg00034.html
https://security.snyk.io/vuln/SNYK-PYTHON-FLASKSECURITY-1293234Exploit, Third Party Advisory
https://snyk.io/blog/url-confusion-vulnerabilities/Technical Description, Third Party Advisory
https://github.com/mattupstate/flask-securityProduct, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2023/08/msg00034.html
https://security.snyk.io/vuln/SNYK-PYTHON-FLASKSECURITY-1293234Exploit, Third Party Advisory
https://snyk.io/blog/url-confusion-vulnerabilities/Technical Description, Third Party Advisory

Timeline

Published: Aug 2, 2022
Last modified: Jun 17, 2026
NVD status: Modified

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