Flask-CORS allows for inconsistent CORS matching

Exploitation

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

CVSS

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

EPSS

• CVE-2024-6844: 0.32% estimated exploitation activity in the next 30 days; percentile 24.98 (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.

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 unquoteplus 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.

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-8vgw-p6qm-5gr7

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-8vgw-p6qm-5gr7

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# Patch Next advisory brief: CVE-2024-6844

Advisory: Flask-CORS allows for inconsistent CORS matching
IDs: CVE-2024-6844, GHSA-8vgw-p6qm-5gr7
Record: https://patchnext.com/advisories/cve-2024-6844 (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-8vgw-p6qm-5gr7 (OSV record GHSA-8vgw-p6qm-5gr7 lists affected ranges: PyPI flask-cors >=0 <6.0.0 (fixed))
- Verified: https://github.com/advisories/GHSA-8vgw-p6qm-5gr7 (GitHub-reviewed advisory GHSA-8vgw-p6qm-5gr7 lists affected ranges: PyPI flask-cors >=0 <=5.0.1)

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