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
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| — | Flask-Security | < unspecified | unspecified |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | flask-security | 5.0.2-1 | — |
| Debian 13 | flask-security | 5.0.2-1 | — |
| Debian 12 | flask-security | 5.0.2-1 | — |
| Debian 10 | flask-security | 1.7.5-2+deb10u1 | DLA-3545-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 22.04 LTS | flask-security | 4.0.0-1ubuntu0.1 | USN-6792-1 |
| Ubuntu 20.04 LTS | flask-security | 1.7.5-2ubuntu0.20.04.1 | USN-6792-1 |
Show 1 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 18.04 LTS | flask-security | 1.7.5-2ubuntu0.18.04.1~esm1 | USN-6792-1 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP4 | python-Flask-Security-Too | 3.4.2-150200.3.6.1 | SUSE-SU-2022:3867-1 |
| SLES 15 SP3 | python-Flask-Security-Too | 3.4.2-150200.3.6.1 | SUSE-SU-2022:3867-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | python-Flask-Security | 5.5.2-1.1 | openSUSE-SU-2024:14555-1 |
| openSUSE Leap 15.4 | python-Flask-Security | 3.0.0-150100.4.3.1 | SUSE-SU-2022:3834-1 |
| openSUSE Leap 15.4 | python-Flask-Security-Too | 3.4.2-150200.3.6.1 | SUSE-SU-2022:3867-1 |
| openSUSE Leap 15.3 | python-Flask-Security | 3.0.0-150100.4.3.1 | SUSE-SU-2022:3834-1 |
| openSUSE Leap 15.3 | python-Flask-Security-Too | 3.4.2-150200.3.6.1 | SUSE-SU-2022:3867-1 |
Affected packages
| Ecosystem | Package | Affected | Fixed | Record |
|---|---|---|---|---|
| PyPI | flask-security | <= 3.0.0 | — | GHSA-cg8c-gc2j-2wf7 |
| PyPI | flask-security | < 5.5.1 | 5.5.1 | PYSEC-2026-809 |
Advisories 5
- DLA-3545-1 flask-security - security update Debian Security (DSA / DLA) · Mar 9, 2026
- USN-6792-1 flask-security vulnerability Ubuntu Security Notices (USN) · Feb 10, 2026
- openSUSE-SU-2024:14555-1 python310-Flask-Security-5.5.2-1.1 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2022:3867-1 Security update for python-Flask-Security-Too SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2022:3834-1 Security update for python-Flask-Security SUSE / openSUSE Security Updates · Feb 4, 2026