# CVE-2021-23385: flask-security: This affects all versions of package Flask-Security

CVE-2021-23385 is fixed in 2 products on 1 platform, first by python3-flask-security 1.7.5-2ubuntu0.18.04.1~esm1, released August 2, 2022. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2021-23385
- Priority: Routine
- CVSS: 6.1 (medium)
- EPSS: 0.0125
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Aug 2, 2022

## 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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | flask-security Debian 12.15 (bookworm) | 5.0.2-1 | [DEBIAN-CVE-2021-23385](https://patchblox.com/security/data/fix/linux/debian-cve-2021-23385.md) | Aug 2, 2022 |
| Linux | flask-security Debian 13.5 (trixie) | 5.0.2-1 | [DEBIAN-CVE-2021-23385](https://patchblox.com/security/data/fix/linux/debian-cve-2021-23385.md) | Aug 2, 2022 |
| Linux | flask-security Debian 14 | 5.0.2-1 | [DEBIAN-CVE-2021-23385](https://patchblox.com/security/data/fix/linux/debian-cve-2021-23385.md) | Aug 2, 2022 |
| Linux | python3-flask-security Ubuntu 18.04.6 LTS (bionic) | 1.7.5-2ubuntu0.18.04.1~esm1 | [python3-flask-security 1.7.5-2ubuntu0.18.04.1~esm1](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-python3-flask-security-1.7.5-2ubuntu0.18.04.1-esm1.md) | Aug 2, 2022 |
| Linux | python3-flask-security Ubuntu 20.04 LTS (focal) | 1.7.5-2ubuntu0.20.04.1 | [python3-flask-security 1.7.5-2ubuntu0.20.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-python3-flask-security-1.7.5-2ubuntu0.20.04.1.md) | Aug 2, 2022 |
| Linux | python3-flask-security Ubuntu 22.04.1 LTS (jammy) | 4.0.0-1ubuntu0.1 | [python3-flask-security 4.0.0-1ubuntu0.1](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-python3-flask-security-4.0.0-1ubuntu0.1.md) | Aug 2, 2022 |

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Data as of 2026-11-08T13:06:02Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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