Open redirect in Flask-Security
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- Required
- Attack complexity
- Low
- Impact type
- Spoofing
- Confidentiality · integrity · availability
- Low · Low · None
- Fix status
- No fix listed
Attack profile from CVSS 3.1 · NVD. Fix status from CNA and GitHub. Impact type from CWE-601.
Summary
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.
Why it matters now
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| — | Flask-Security | all versions | — | No fix listed | CNA |
| — | Flask-Security (PyPI) | up to 3.0.0 | — | No fix listed | GHSA-cg8c-gc2j-2wf7 |
- Flask-Security Vendor— Affected all versions Fixed in — No fix listed CNA
- Flask-Security (PyPI) Vendor— Affected up to 3.0.0 Fixed in — No fix listed GHSA-cg8c-gc2j-2wf7
CPE configurations NVD · 1
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:flask-security_project:flask-security:*:*:*:*:*:*:*:* | all versions | Vulnerable | Flask-security Project |
- cpe:2.3:a:flask-security_project:flask-security:*:*:*:*:*:*:*:* Versions all versions Vulnerable ·Flask-security Project
Remediation
No fixed version listed by the sources yet.
Vendor assessments
Timeline
- 2026-10-02 Threatist record created from CVE-2021-23385
- 2026-10-03 Alias added: GHSA-cg8c-gc2j-2wf7
References
More Flask-security Project Flask-security vulnerabilities
- TI-2021-12287 Open redirect in Flask-Middleware flask-security CVSS 3.1MEDIUM 6.1
Sources
- CVE-2021-23385 · CVE Program
- CVE-2021-23385 · NVD
- FIRST EPSS
- GHSA-cg8c-gc2j-2wf7 · GitHub Advisory Database · CC BY 4.0
- CVE-2021-23385 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences