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MEDIUM severity

CVE-2024-6866 — flask-cors

MEDIUMFix: corydolphin/flask-cors@eb39516

CVE-2024-6866 is a medium-severity (CVSS 5.3) CWE-178 vulnerability in flask-cors. A fix is available for flask-cors — see the affected versions and patch details below.

Case-Insensitive Path Matching in corydolphin/flask-cors

Also known asGHSA-43qf-4rqw-9q2gPYSEC-2026-1383
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Nov 8, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

Proof-of-concept exploit code exists

  • CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.

Exploitation and automatability from CISA’s SSVC triage for CVE-2024-6866.

EPSS Exploitation Probability

via FIRST.org ↗
0.7%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs54th percentile — riskier than 54% of all scored CVEsHighest risk
0.00%0.41%0.81%1.22%0.1%0.7%May 26Sep 26Nov 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected
🐍flask-cors

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.

Description

corydolphin/flask-cors version 4.01 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.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
🐍PyPIflask-corsall versions6.0.0pip install --upgrade 'flask-cors==6.0.0'

Affected Products

1 product · 1 configurations
Application
flask-corsflask-cors_project
1 version
4.0.1

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for flask-cors, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update flask-cors to 6.0.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2024-6866 is resolved across your whole dependency graph.

  3. Workarounds

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Frequently Asked Questions

corydolphin/flask-cors version 4.01 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.
O3 Security · Impact-Aware SCA

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CVE-2024-6866: flask-cors — Fixed in 6.0.0