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MEDIUM5.3

PYSEC-2026-1383

Flask-CORS vulnerable to Improper Handling of Case Sensitivity

Quick fix

PYSEC-2026-1383 — flask-cors: upgrade to the fixed version with the command below.

pip install --upgrade 'flask-cors>=6.0.0'

Details

corydolphin/flask-cors version 5.0.1 contains a vulnerability where the request path matching is case-insensitive due to the use of the `try_match` function, which is originally intended for matching hosts. This results in a mismatch because paths in URLs are case-sensitive, but the regex matching treats them as case-insensitive. This misconfiguration can lead to significant security vulnerabilities, allowing unauthorized origins to access paths meant to be restricted, resulting in data exposure and potential data leaks.

Are you affected?

Enter the version of the package you're using.

Affected packages

PyPI/flask-cors
Introduced in: 0Fixed in: 6.0.0
Fixpip install --upgrade 'flask-cors>=6.0.0'

References