Cross-origin data exposure via case-insensitive path matching
Published Mar 20, 2025 · Updated Nov 3, 2025
Improper case handling in Flask-CORS 5.0.1 and earlier allows remote attackers to read restricted data via cross-origin requests. The cors_after_request handler passes URL paths to try_match, whose regex branch applies re.IGNORECASE and can select a more permissive CORS rule for a differently cased path. Exploitation requires a user's browser to request an application with case-distinct paths and resource-specific CORS policies, exposing response data only.
Summary
What happened
Improper case handling in Flask-CORS 5.0.1 and earlier allows remote attackers to read restricted data via cross-origin requests. The cors_after_request handler passes URL paths to try_match, whose regex branch applies re.IGNORECASE and can select a more permissive CORS rule for a differently cased path. Exploitation requires a user's browser to request an application with case-distinct paths and resource-specific CORS policies, exposing response data only.
The record
- CVE
- CVE-2024-6866
- Published
- Mar 20, 2025
- Updated
- Nov 3, 2025
- Vendor
- Cory Dolphin
- Product
- Flask-CORS
- Classifications
- CWE-178
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Mar 20, 2025CVE publishedPublication date reported by the CVE source.
- Nov 3, 2025Record updatedLatest update available in the CVE record.
Exploitability
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- Affected versionversion=unspecified <=latest
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Published CVSS scores
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Attacks
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Technologies
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