Skip to main content

Early Access — Mondoo Vulnerability Intelligence is currently in preview.

Mondoo Vulnerability Intelligence

Curated by Mondoo Research, enhanced with AI

Resources

Search Vulnerabilities
Trending CVEs
Browse Ecosystems
Terminology
Blog

Open Source

cnquery
cnspec

Star us on GitHub!

Company

Mondoo Platform
About
Contact

© 2026 Mondoo, Inc.

Privacy Policy Terms of Service Imprint

Vulnerability Intelligence

CVE-2025-66418

HIGH8.9

urllib3 allows an unbounded number of links in the decompression chain

Published Dec 5, 2025

Modified 1 months ago

No fix available

Details

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.

References

WEBhttps://github.com/urllib3/urllib3/commit/24d7b67eac89f94e11003424bcf0d8f7b72222a8 WEBhttps://github.com/urllib3/urllib3/security/advisories/GHSA-gm62-xv2j-4w53 ADVISORYhttps://www.cve.org/CVERecord?id=CVE-2025-66418

CVSS Analysis

CVSS v4.0

8.9

Exploitability

Attack Vector

NetworkAV:N

Attack Complexity

LowAC:L

Attack Requirements

PresentAT:P

Privileges Required

NonePR:N

User Interaction

NoneUI:N

Vulnerable System

Vuln. Confidentiality

NoneVC:N

Vuln. Integrity

NoneVI:N

Vuln. Availability

HighVA:H

Subsequent System

Subseq. Confidentiality

NoneSC:N

Subseq. Integrity

NoneSI:N

Subseq. Availability

HighSA:H

8.9/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

Weakness Type (CWE)

Resource Management

Allocation without Limits

Ecosystems

Timeline

PublishedDec 5, 2025

ModifiedDec 5, 2025

CVE-2025-66418 | Mondoo Vulnerability Intelligence