What’s Vulnerable › Vulnerabilities

CVE-2021-23385: Open Redirect

• Severity: medium (CVSS 6.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.2% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2022-08-02 · updated 2026-06-17
• Weakness: CWE-601

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.

Affected products

• Flask-Security: all versions

References

• https://github.com/mattupstate/flask-security
• https://lists.debian.org/debian-lts-announce/2023/08/msg00034.html
• https://security.snyk.io/vuln/SNYK-PYTHON-FLASKSECURITY-1293234
• https://snyk.io/blog/url-confusion-vulnerabilities/
• https://github.com/mattupstate/flask-security
• https://lists.debian.org/debian-lts-announce/2023/08/msg00034.html
• https://security.snyk.io/vuln/SNYK-PYTHON-FLASKSECURITY-1293234
• https://snyk.io/blog/url-confusion-vulnerabilities/

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