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CVE-2023-46728: Remove support for Gopher protocol (#1092) · squid-cache/squid@6ea12e8
Squid is a caching proxy for the Web supporting HTTP, HTTPS, FTP, and more. Due to a NULL pointer dereference bug Squid is vulnerable to a Denial of Service attack against Squid’s Gopher gateway. The gopher protocol is always available and enabled in Squid prior to Squid 6.0.1. Responses triggering this bug are possible to be received from any gopher server, even those without malicious intent. Gopher support has been removed in Squid version 6.0.1. Users are advised to upgrade. Users unable to upgrade should reject all gopher URL requests.
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Remove support for Gopher protocol (#1092)
Gopher code quality remains too low for production use in most environments. The code is a persistent source of vulnerabilities and fixing it requires significant effort. We should not be spending scarce Project resources on improving that code, especially given the lack of strong demand for Gopher support.
With this change, Gopher requests will be handled like any other request with an unknown (to Squid) protocol. For example, HTTP requests with Gopher URI scheme result in ERR_UNSUP_REQ.
Default Squid configuration still considers TCP port 70 "safe". The corresponding Safe_ports ACL rule has not been removed for consistency sake: We consider WAIS port safe even though Squid refuses to forward WAIS requests:
acl Safe\_ports port 70 # gopher
acl Safe\_ports port 210 # wais
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