CVSS 3.1
6.1 mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:NCVE-2021-23385
Medium (6.1) in flask-security project flask-security. EPSS 1.2% chance of exploitation in the next 30 days. Fixed in flask-security 5.5.1.
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.
Severity
- EPSS
- 1.2% chance of exploitation in the next 30 days; higher than 69% of CVEs (scores of 2026-10-31)
- CWE
- CWE-601
- Published
- Modified
- Record from
- the NVD, synced
Affected
- flask-security_project:flask-security
Packages (OSV)
| Advisory | Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|---|
| GHSA-cg8c-gc2j-2wf7 | PyPI | flask-security | <=3.0.0 | no fix published |
| PYSEC-2026-809 | PyPI | flask-security | <5.5.1 | 5.5.1 |