Flask-CORS vulnerable to Improper Handling of Case Sensitivity

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

5.3 · CVSS:3.0/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N

EPSS

• CVE-2024-6866: 0.72% estimated exploitation activity in the next 30 days; percentile 53.97 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

corydolphin/flask-cors version 5.0.1 contains a vulnerability where the request path matching is case-insensitive due to the use of the trymatch 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.

Published by the source

20 Mar 2025, 12:32 UTC

Last modified by the source

10 Sep 2026, 03:50 UTC

Source last checked

26 Oct 2026, 13:35 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-43qf-4rqw-9q2g

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-43qf-4rqw-9q2g

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# Patch Next advisory brief: CVE-2024-6866

Advisory: Flask-CORS vulnerable to Improper Handling of Case Sensitivity
IDs: CVE-2024-6866, GHSA-43qf-4rqw-9q2g
Record: https://patchnext.com/advisories/cve-2024-6866 (revision 2, source checked 26 Oct 2026, 13:35 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: flask-cors 6.0.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI flask-cors: affected <= 5.0.1; fixed in 6.0.0

## Suggested inspection (read-only)
- `python -m pip show flask-cors`: prints the installed version. Run with the environment that serves production active.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on flask-cors.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-43qf-4rqw-9q2g (OSV record GHSA-43qf-4rqw-9q2g lists affected ranges: PyPI flask-cors >=0 <6.0.0 (fixed))
- Verified: https://github.com/advisories/GHSA-43qf-4rqw-9q2g (GitHub-reviewed advisory GHSA-43qf-4rqw-9q2g lists affected ranges: PyPI flask-cors >=0 <=5.0.1)

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