---
id: CVE-2024-6866
aliases:
  - GHSA-43qf-4rqw-9q2g
  - PYSEC-2026-1383
title: Flask-CORS vulnerable to Improper Handling of Case Sensitivity
summary: Flask-CORS vulnerable to Improper Handling of Case Sensitivity
severity: medium
cvss: 5.3
cvssVector: 'CVSS:3.0/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N'
vendor: flask-cors
product: flask-cors
ecosystem: pip
affected:
  - flask-cors < 6.0.0
patched:
  - flask-cors 6.0.0
published: '2025-03-20'
updated: '2026-09-10'
sourceUpdated: '2026-09-10T03:50:56.795708366Z'
source: OSV
sourceUrl: 'https://osv.dev/vulnerability/GHSA-43qf-4rqw-9q2g'
references:
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2024-6866'
  - url: >-
      https://github.com/corydolphin/flask-cors/commit/eb39516a3c96b90d0ae5f51293972395ec3ef358
  - url: 'https://github.com/corydolphin/flask-cors'
  - url: >-
      https://github.com/corydolphin/flask-cors/blob/4.0.1/flask_cors/extension.py#L195
  - url: 'https://huntr.com/bounties/808c11af-faee-43a8-824b-b5ab4f62b9e6'
  - url: 'https://lists.debian.org/debian-lts-announce/2025/05/msg00049.html'
tags:
  - osv
  - pip
epss: 0.00706
epssPercentile: 0.51306
ingestedAt: '2026-07-08T18:25:45.244Z'
---

## Overview

corydolphin/flask-cors version 5.0.1 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

- `flask-cors < 6.0.0`

## Remediation

Upgrade to a patched release:

- `flask-cors 6.0.0`