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CVE-2021-23401

nvd nist
Published: Jul 5, 2021Modified: Jun 17, 2026

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6.1
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Exploitability: 2.8 / Impact: 2.7
Source: NVD

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.

Affected (1)

Flask User Project
1 product
Flask User
Configuration A
1 vulnerable
Vulnerable SoftwareAffected Versions
Flask User
All versions

Related CWEs

CWE-601
URL Redirection to Untrusted Site ('Open Redirect')
A web application accepts a user-controlled input that specifies a link to an external site, and uses that link in a Redirect. This simplifies phishing attacks.

References (6)

Source: report@snyk.io
ProductThird Party Advisory
Source: report@snyk.io
ExploitThird Party Advisory
Source: report@snyk.io
Third Party Advisory
Source: af854a3a-2127-422b-91ae-364da2661108
ProductThird Party Advisory
Source: af854a3a-2127-422b-91ae-364da2661108
ExploitThird Party Advisory
Source: af854a3a-2127-422b-91ae-364da2661108
Third Party Advisory

Timeline

No history available yet.