Internationalized Domain Names in Applications (IDNA) vulnerable to denial of service from specially crafted inputs to idna.encode
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
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Python (PyPI) | idna | < 3.7 | 3.7 |
References
- https://huntr.com/bounties/93d78d07-d791-4b39-a845-cbfabc44aadb
- https://github.com/kjd/idna/commit/1d365e17e10d72d0b7876316fc7b9ca0eebdd38d
- https://github.com/advisories/GHSA-jjg7-2v4v-x38h
- https://github.com/kjd/idna/security/advisories/GHSA-jjg7-2v4v-x38h
- https://nvd.nist.gov/vuln/detail/CVE-2024-3651
- https://github.com/kjd/idna
- https://github.com/pypa/advisory-database/tree/main/vulns/idna/PYSEC-2024-60.yaml
- https://lists.debian.org/debian-lts-announce/2024/05/msg00006.html
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/4YQUPYH3SVZ5GFF2CDQ55FCM575AZTF2
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/F2S5E23N6E52S46KGNYTDFB75LOC4N4D
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/S5IDLLD2IKSIVRBSLB34WTSYGLMWUFWF
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/ULSC7HBJKXB3BZV367WM5BR6DFEC4Z43
- CVSS vector
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H- Weakness (CWE)
CWE-1333, CWE-400- Platform
- Python (PyPI)
- Package
idna- Disclosed
- 11.04.2024
- Updated
- 11.10.2026 15:17
Sources and licenses
OSV / GitHub Advisory Database - PYSEC-2024-60 - PyPA Advisory Database; CC BY 4.0
OSV / GitHub Advisory Database - GHSA-jjg7-2v4v-x38h - CC BY 4.0
Vulnerability history: idna
All published vulnerabilities of this package (Python (PyPI)), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 2
- First → latest
- 04.2024 05.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- Medium 2
Disclosures per year
- 2024: 1
- 2025: 0
- 2026: 1
-
Internationalized Domain Names in Applications (IDNA) vulnerable to denial of service from specially crafted inputs to idna.encode this entry
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