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CVE-2021-23393

5.4 mediumEPSS 0.7%

Medium (5.4) in flask unchained project flask unchained. EPSS 0.7% chance of exploitation in the next 30 days. Fixed in flask-unchained 0.9.0.

This affects the package Flask-Unchained before 0.9.0. When using the the _validate_redirect_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. 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.

Severity

CVSS 3.1

5.4 medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N
EPSS
0.7% chance of exploitation in the next 30 days; higher than 53% of CVEs (scores of 2026-10-31)
CWE
CWE-601
Published
Modified
Record from
the NVD, synced

Affected

Packages (OSV)

AdvisoryEcosystemPackageAffectedFixed in
GHSA-pjc4-3w99-j7v4PyPIflask-unchained<0.9.00.9.0
PYSEC-2021-96PyPIflask-unchained<0.9.00.9.0

References

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