How severe is CVE-2024-3651?

CVE-2024-3651 has a CVSS score of 6.2/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2024-3651?

CVE-2024-3651 affects the following packages: idna (PyPI). Ecosystems affected: PyPI.

How do I fix CVE-2024-3651?

Update idna to 3.7 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2024-3651 is resolved across your whole dependency graph.

How do I detect CVE-2024-3651 in my PyPI dependencies?

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

How do I mitigate CVE-2024-3651 if there is no patch (or I can't update yet)?

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.

Is CVE-2024-3651 actively exploited in the wild?

Yes. There are 1 known exploit references for CVE-2024-3651, including 1 in-the-wild exploitation observed on GitHub and other sources. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for CVE-2024-3651?

CVE-2024-3651 has an EPSS (Exploit Prediction Scoring System) score of 1.4%, placing it in the 72th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2024-3651?

CVE-2024-3651 is classified as CWE-1333 (CWE-1333). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2024-3651 published, and has it been updated?

CVE-2024-3651 was published on July 7, 2024 and was last updated on October 28, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐍

🐍 PyPI

Not in CISA KEV

MEDIUM severity

CVE-2024-3651 — idna

MEDIUMFix: kjd/idna@1d365e1

CVE-2024-3651 is a medium-severity (CVSS 6.2) CWE-1333 vulnerability in idna. 1 public exploit or proof-of-concept reference is indexed, so weaponization risk is real. A fix is available for idna — see the affected versions and patch details below.

Denial of Service via Quadratic Complexity in kjd/idna

Also known asGHSA-jjg7-2v4v-x38hPYSEC-2024-60

Published

Jul 7, 2024

Updated

Oct 28, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

1 known

Exploitation data as of Nov 8, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2024-3651.

EPSS Exploitation Probability

via FIRST.org ↗

1.4%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs72th percentile — riskier than 72% of all scored CVEsHighest risk

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

🐍idna

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

Impact

A specially crafted argument to the idna.encode() function could consume significant resources. This may lead to a denial-of-service.

Patches

The function has been refined to reject such strings without the associated resource consumption in version 3.7.

Workarounds

Domain names cannot exceed 253 characters in length, if this length limit is enforced prior to passing the domain to the idna.encode() function it should no longer consume significant resources. This is triggered by arbitrarily large inputs that would not occur in normal usage, but may be passed to the library assuming there is no preliminary input validation by the higher-level application.

References

https://huntr.com/bounties/93d78d07-d791-4b39-a845-cbfabc44aadb

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐍PyPI	`idna`	all versions	3.7`pip install --upgrade 'idna==3.7'`

Affected Products

1 product · 1 configurations

Application

internationalized domain names in applicationskjd

≥ 0.2 && < 3.7

range

Exploits & PoCs

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

A vulnerability was identified in the kjd/idna library, specifically wit…

huntr.comNVDJul 2024

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for idna, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update idna to 3.7 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2024-3651 is resolved across your whole dependency graph.
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.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatModerate

The vulnerability in the idna.encode() function, allowing for resource consumption via specially crafted arguments, is categorized as a moderate severity issue due to its potential impact on system availability rather than data integrity or confidentiality. While the vulnerability can lead to a denial-of-service…

Workaround published by Red Hat

Mitigation for this issue is either not available or the currently available options don't meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.

Source: Red Hat security advisory for CVE-2024-3651 (CC BY 4.0)

Product	Fixed in	Advisory
Red Hat Ansible Automation Platform 2.4 for RHEL 8	`python3x-idna-0:3.7-1.el8ap`	RHSA-2024:3781
Red Hat Enterprise Linux 7 Extended Lifecycle Support	`python-idna-0:2.4-2.el7_9`	RHSA-2024:8365
Red Hat Enterprise Linux 8	`python39:3.9-8100020240516111311.d47b87a4`	RHSA-2024:3466
Red Hat Enterprise Linux 8	`python-idna-0:2.5-7.el8_10`	RHSA-2024:4260
Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support	`python-idna-0:2.5-5.el8_6.1`	RHSA-2024:3552
Red Hat Enterprise Linux 8.8 Extended Update Support	`python-idna-0:2.5-5.el8_8.1`	RHSA-2024:3543
Red Hat Enterprise Linux 9	`python-idna-0:2.10-7.el9_4.1`	RHSA-2024:3846

Frequently Asked Questions

### Impact A specially crafted argument to the `idna.encode()` function could consume significant resources. This may lead to a denial-of-service. ### Patches The function has been refined to reject such strings without the associated resource consumption in version 3.7. ### Workarounds Domain names cannot exceed 253 characters in length, if this length limit is enforced prior to passing the domain to the `idna.encode()` function it should no longer consume significant resources. This is triggered by arbitrarily large inputs that would not occur in normal usage, but may be passed to the libr

O3 Security · Impact-Aware SCA

Is CVE-2024-3651 in your dependencies?

Find it across PyPI, including transitive dependencies.

Scan my dependencies How O3 SCA works