GHSA-65pc-fj4g-8rjx

Suggest an improvement
Source
https://github.com/advisories/GHSA-65pc-fj4g-8rjx
Import Source
https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/05/GHSA-65pc-fj4g-8rjx/GHSA-65pc-fj4g-8rjx.json
JSON Data
https://api.osv.dev/v1/vulns/GHSA-65pc-fj4g-8rjx
Aliases
  • CVE-2026-45409
Downstream
Related
Published
2026-05-19T14:34:32Z
Modified
2026-06-09T12:00:13.346264116Z
Severity
  • 6.9 (Medium) CVSS_V4 - CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N CVSS Calculator
Summary
Internationalized Domain Names in Applications (IDNA): Specially crafted inputs to idna.encode() can bypass CVE-2024-3651 fix
Details

This is the same issue as CVE-2024-3651, however the original remediation in 2024 was not a complete fix. Payloads such as "\u0660" * N or "\u30fb" * N + "\u6f22" utilize the valid_contexto function prior to length rejection, and for high values of N will take a long time to process.

Impact

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

Patches

Starting in version 3.14, the function rejects long inputs as soon as practicable prior to any further processing to minimize resource consumption. In version 3.15, this approach was extended to lesser used alternate functions (i.e. per-label conversions and codec support).

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.

Database specific 
{
    "github_reviewed_at": "2026-05-19T14:34:32Z",
    "cwe_ids": [
        "CWE-1333"
    ],
    "severity": "MODERATE",
    "github_reviewed": true,
    "nvd_published_at": "2026-06-05T23:16:43Z"
}
References

Affected packages

PyPI / idna

Package

Name
idna
View open source insights on deps.dev
Purl
pkg:pypi/idna

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected
Fixed
3.15

Affected versions

0.*
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.*
1.0
1.1
2.*
2.0
2.1
2.2
2.3
2.4
2.5
2.6
2.7
2.8
2.9
2.10
3.*
3.0
3.1
3.2
3.3
3.4
3.5
3.6
3.7
3.8
3.9
3.10
3.11
3.12
3.13
3.14

Database specific

source 
"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/05/GHSA-65pc-fj4g-8rjx/GHSA-65pc-fj4g-8rjx.json"