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?
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Affected packages
References
- https://nvd.nist.gov/vuln/detail/CVE-2024-6866[ADVISORY]
- https://github.com/corydolphin/flask-cors/commit/eb39516a3c96b90d0ae5f51293972395ec3ef358[WEB]
- https://github.com/corydolphin/flask-cors[PACKAGE]
- https://github.com/corydolphin/flask-cors/blob/4.0.1/flask_cors/extension.py#L195[WEB]
- https://huntr.com/bounties/808c11af-faee-43a8-824b-b5ab4f62b9e6[WEB]
- https://lists.debian.org/debian-lts-announce/2025/05/msg00049.html[WEB]
- https://pypi.org/project/flask-cors[PACKAGE]
- https://github.com/advisories/GHSA-43qf-4rqw-9q2g[ADVISORY]