---
cve: "CVE-2025-66418"
severity: "HIGH"
cvss: 8.9
epss: "69%"
vendor: "urllib3"
kev: false
exploited: false
published: "2025-12-05 16:15:51"
tags: [cve, security, high]
source: tsecurity.de CVE-Dossier
exported: "2026-09-06T00:50:50+02:00"
---

# CVE-2025-66418

> 8.9 HIGH · 🧪 PoC

## Beschreibung

urllib3 is a user-friendly HTTP client library for Python. Starting in version 1.24 and prior to 2.6.0, the number of links in the decompression chain was unbounded allowing a malicious server to insert a virtually unlimited number of compression steps leading to high CPU usage and massive memory allocation for the decompressed data. This vulnerability is fixed in 2.6.0.

## CVSS-Vektor

```
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Gering | bad |
| PR Privilegien | Keine | bad |
| UI Interaktion | Keine | bad |

## Patch verfügbar (OSV)

- 720f484b605f18887a48eef448d0084e2b76902d (Commit)
- 24d7b67eac89f94e11003424bcf0d8f7b72222a8 (Commit)

## Referenzen

- <https://github.com/urllib3/urllib3/security/advisories/GHSA-gm62-xv2j-4w53>
- <https://github.com/urllib3/urllib3/commit/24d7b67eac89f94e11003424bcf0d8f7b72222a8>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2025-66418) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_