CVE-2024-6221: A vulnerability in corydolphin/flask-cors version 4.0.1 allows the `Access-Control-Allow-Private-Network` CORS

This week

HIGH 7.5REMOTEDOWNGRADE

CVE-2024-6221 is a high-severity flaw (CVSS 7.5) affecting flask-cors. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

A vulnerability in corydolphin/flask-cors version 4.0.1 allows the `Access-Control-Allow-Private-Network` CORS header to be set to true by default. This behavior can expose private network resources to unauthorized external access, leading to significant security risks such as data breaches, unauthorized access to sensitive information, and potential network intrusions.

Why this priority

High severity
Public exploit reference
Remotely exploitable, no login, no user action

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.7% (top 46%)
CISA exploited list	No
Weakness	CWE-284
Published	2024-08-18
Last modified	2026-06-17

Publisher (CNA): huntr.dev · Vendor: corydolphin

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2024-08-18 19:15 UTCPublished CVE record published
2026-06-17 08:17 UTCUpdated Record last modified

corydolphin flask-cors DOWNGRADE

Affected: 4.0.1

Fixed in: no fixed release known

Safe to downgrade to: a release before 4.0.1

1. Check installed version

apt-cache policy flask-cors || rpm -q flask-cors || flask-cors --version

2. No fixed release: DOWNGRADE to a release before 4.0.1 (Debian / Ubuntu)

apt-cache madison flask-cors sudo apt install flask-cors=<VERSION_BEFORE_4.0.1> sudo apt-mark hold flask-cors

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list flask-cors sudo dnf downgrade flask-cors-<VERSION_BEFORE_4.0.1> sudo dnf versionlock add flask-cors

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2024-6221?

flask-cors: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2024-6221 being exploited?

CVE-2024-6221 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2024-6221 affect?

CVE-2024-6221 affects flask-cors. Severity is high (CVSS 7.5). A vulnerability in corydolphin/flask-cors version 4.0.1 allows the `Access-Control-Allow-Private-Network` CORS header to be set to true by default. This behavior can expose private network resources to unauthorized external access, leading

How urgent is CVE-2024-6221?

Priority 50/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action

Software pages

Flask vulnerabilities

Related CVEs

CVE-2024-6866 HIGH 7.5 DOWNGRADE corydolphin/flask-cors version 4.01 contains a vulnerability where the request path matching is case-insensiti
CVE-2024-6844 MEDIUM 5.3 DOWNGRADE A vulnerability in corydolphin/flask-cors version 4.0.1 allows for inconsistent CORS matching due to the handl
CVE-2024-6839 MEDIUM 5.3 DOWNGRADE corydolphin/flask-cors version 4.0.1 contains an improper regex path matching vulnerability
CVE-2024-1681 MEDIUM 5.3 DOWNGRADE corydolphin/flask-cors is vulnerable to log injection when the log level is set to debug

References

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