Flask-CORS allows for inconsistent CORS matching
A vulnerability in corydolphin/flask-cors version 5.0.1 allows for inconsistent CORS matching due to the handling of the '+' character in URL paths. The request.path is passed through the unquote_plus function, which converts the '+' character to a space ' '. This behavior leads to incorrect path normalization, causing potential mismatches in CORS configuration. As a result, endpoints may not be matched correctly to their CORS settings, leading to unexpected CORS policy application. This can cause unauthorized cross-origin access or block valid requests, creating security vulnerabilities and usability issues.
Affected software
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| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Python (PyPI) | flask-cors | < 6.0.0 | 6.0.0 |
References
- https://nvd.nist.gov/vuln/detail/CVE-2024-6844
- https://github.com/corydolphin/flask-cors/commit/35d875319621bd129a38b2b823abf4a2f6cda536
- https://github.com/corydolphin/flask-cors
- https://github.com/corydolphin/flask-cors/blob/main/flask_cors/extension.py#L193
- https://huntr.com/bounties/731a6cd4-d05f-4fe6-8f5b-fe088d7b34e0
- https://lists.debian.org/debian-lts-announce/2025/05/msg00049.html
- https://pypi.org/project/flask-cors
- https://github.com/advisories/GHSA-8vgw-p6qm-5gr7
- CVSS vector
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N- Weakness (CWE)
CWE-346- Platform
- Python (PyPI)
- Package
flask-cors- Disclosed
- 20.03.2025
- Updated
- 11.10.2026 15:17
Sources and licenses
OSV / GitHub Advisory Database - PYSEC-2026-1385 - PyPA Advisory Database; CC BY 4.0
OSV / GitHub Advisory Database - GHSA-8vgw-p6qm-5gr7 - CC BY 4.0
Vulnerability history: flask-cors
All published vulnerabilities of this package (Python (PyPI)), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 6
- First → latest
- 08.2020 03.2025
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- High 2
- Medium 4
Disclosures per year
- 2020: 1
- 2021: 0
- 2022: 0
- 2023: 0
- 2024: 2
- 2025: 3
- 2026: 0
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Flask-CORS allows for inconsistent CORS matching this entry
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