Squid is a caching proxy for the Web supporting HTTP, HTTPS, FTP, and more. Affected versions of squid are subject to a a Use-After-Free bug which can lead to a Denial of Service attack via collapsed forwarding. All versions of Squid from 3.5 up to and including 5.9 configured with "collapsed_forwarding on" are vulnerable. Configurations with "collapsed_forwarding off" or without a "collapsed_forwarding" directive are not vulnerable. This bug is fixed by Squid version 6.0.1. Users are advised to upgrade. Users unable to upgrade should remove all collapsed_forwarding lines from their squid.conf.
This vulnerability carries a HIGH severity rating with a CVSS v3.1 score of 8.6, indicating it can be exploited remotely over the network with relatively low complexity without requiring user interaction and does not require pre-existing privileges . The vulnerability impacts and availability (service disruption) for affected systems. Impacting 1 product from squid-cache organizations running these solutions should prioritize assessment and patching.
Reported in 2023, this vulnerability emerged during an era marked by increased sophistication in supply chain attacks, cloud infrastructure vulnerabilities, and software-as-a-service (SaaS) security challenges. Security practices during this period emphasized zero-trust architectures, container security, and API protection.
2023-12-04T23:15:27.477
2024-11-21T08:33:11.613
Modified
CVSSv3.1: 8.6 (HIGH)
| Type | Vendor | Product | Version/Range | Vulnerable? |
|---|---|---|---|---|
| Application | squid-cache | squid | ≤ 5.9 | Yes |
SecUtils normalizes and enriches National Vulnerability Database (NVD) records by standardizing vendor and product identifiers, aggregating vulnerability metadata from both NVD and MITRE sources, and providing structured context for security teams. For squid-cache's affected products, we extract Common Platform Enumeration (CPE) data, Common Weakness Enumeration (CWE) classifications, CVSS severity metrics, and reference data to enable rapid vulnerability prioritization and asset correlation. This record contains no exploit code, proof-of-concept instructions, or attack methodologies—only defensive intelligence necessary for patch management, risk assessment, and security operations.