CVE-2021-23401 Open Redirect
Attackers can redirect users to arbitrary URLs via malformed slashes in Flask-User, requiring non-default WSGI server configurations.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2021-23401?
CVE-2021-23401 is a medium-severity vulnerability in Flask-User, published on 5 Jul 2021. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
This affects all versions of package Flask-User. When using the make_safe_url function, 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 or \\\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.
Weakness: CWE-601
Which versions are affected by CVE-2021-23401?
3 open source packages ship an affected version, including flask-user and Flask-User. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
flask-user PyPI | All versions | None |
flask-user PyPI | All versions to 1.0.2.2 | None |
Flask-User PyPI | All versions to 1.0.2.2 | None |
Products include Flask-User Project Flask-User.
How do I fix CVE-2021-23401?
No fix has been published for CVE-2021-23401 yet. Limit exposure of the affected software until one is available.
Is CVE-2021-23401 being exploited?
There is no known exploitation of CVE-2021-23401 in the wild and no public exploit code.
Sources
Also known as GHSA-4298-89hc-6rfv, PYSEC-2021-337, SNYK-PYTHON-FLASKUSER-1293188.