Squid is a third-party, open-source, add-on package for both pfSense® Plus and pfSense CE software that functions as a caching proxy (caching and reusing frequently-accessed web content to reduce the use of bandwidth).
Recent reports have identified a large number of unresolved security-related vulnerabilities in Squid. Because the security of our users is of utmost importance to us, we highly recommend that all users uninstall Squid.
Netgate® now considers the add-on package for Squid, and the related add-on packages for Lightsquid and SquidGuard, to be 'deprecated.' We have determined that while these add-on packages will work in version 23.09 of pfSense Plus software and version 2.7.1 of pfSense CE software, the next major release of each product will no longer support their use, and they will be removed from the list of available add-on packages.
Reports of vulnerabilities:
https://www.theregister.com/2023/10/13/squid_proxy_bugs_remain_unfixed
https://joshua.hu/squid-security-audit-35-0days-45-exploits
Information About Squid:
http://www.squid-cache.org/