Description
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.
Remediation
References
Related Vulnerabilities
Coppermine Exposure of Sensitive Information to an Unauthorized Actor Vulnerability (CVE-2008-7187)
PHP Other Vulnerability (CVE-2007-1718)
Apache Tomcat Insertion of Sensitive Information into Log File Vulnerability (CVE-2026-34487)
WordPress Plugin YITH PayPal Express Checkout for WooCommerce Security Bypass (1.2.5)