---
schema_version: '1.0'
id: security-20260711-3ab8f0
url: https://osv.dev/vulnerability/GHSA-65pc-fj4g-8rjx
url_hash: 3ab8f0c75ee4f1c339944c8ae83ef8abfcb3758fd614e91674f51b25021161c3
canonical_url: https://osv.dev/vulnerability/GHSA-65pc-fj4g-8rjx
source: osv:ghsa
category: security/library
category_raw: cve/library
region: null
tags:
- cve
- CVE-2026-45409
- GHSA-65pc-fj4g-8rjx
- severity:CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
- idna
- PyPI
lang: en
published_at: '2026-05-19T14:34:32Z'
fetched_at: '2026-07-11T06:37:17Z'
updated_at: '2026-07-11T06:39:11Z'
status: published
content_hash: d7492b07c344c7eba29bc6b5813799428f821b56b2627275cac84e5c5f521aee
license_note: full
summary: 'Internationalized Domain Names in Applications (IDNA): Specially crafted
  inputs to idna.encode() can bypass CVE-2024-3651 fix'
summary_source: rss
summary_en: 'Internationalized Domain Names in Applications (IDNA): Specially crafted
  inputs to idna.encode() can bypass CVE-2024-3651 fix'
entities:
- name: τ²-bench airline domain
  type: location
key_facts: []
related: []
related_auto: []
title: 'CVE-2026-45409: Internationalized Domain Names in Applications (IDNA): Specially
  crafted inputs to idna.encode() can bypass CVE-2024-3651 fix'
---

# CVE-2026-45409: Internationalized Domain Names in Applications (IDNA): Specially crafted inputs to idna.encode() can bypass CVE-2024-3651 fix

## TL;DR
Internationalized Domain Names in Applications (IDNA): Specially crafted inputs to idna.encode() can bypass CVE-2024-3651 fix

## Key Points
- cve / CVE-2026-45409 / GHSA-65pc-fj4g-8rjx / severity:CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L / idna / PyPI

## Details
**Severity:** CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
**Advisory:** GHSA-65pc-fj4g-8rjx (CVE-2026-45409)

**Affected (your watchlist):**
- `PyPI:idna` 3.11 → fixed in 3.15 [docker/docker-llmwiki+docker/docker-mcp]
- `PyPI:idna` 3.13 → fixed in 3.15 [docker/local]

**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.

**References:**
- https://github.com/kjd/idna/security/advisories/GHSA-65pc-fj4g-8rjx
- https://nvd.nist.gov/vuln/detail/CVE-2026-45409
- https://github.com/kjd/idna
- https://github.com/pypa/advisory-database/tree/main/vulns/idna/PYSEC-2026-215.yaml

_Data: OSV.dev (upstream: ghsa) — https://osv.dev/vulnerability/GHSA-65pc-fj4g-8rjx_

## Source
元記事: [CVE-2026-45409: Internationalized Domain Names in Applications (IDNA): Specially crafted inputs to idna.encode() can bypass CVE-2024-3651 fix](https://osv.dev/vulnerability/GHSA-65pc-fj4g-8rjx) — published 2026-05-19T14:34:32Z