An issue was discovered in Squid before 4.9. URN response handling in Squid suffers from a heap-based buffer overflow. When receiving data from a remote server in response to an URN request, Squid fails to ensure that the response can fit within the buffer. This leads to attacker controlled data overflowing in the heap.

Due to incorrect string termination, Squid cachemgr.cgi 4.0 through 4.7 may access unallocated memory. On systems with memory access protections, this can cause the CGI process to terminate unexpectedly, resulting in a denial of service for all clients using it.

An issue was discovered in Squid 4.0.23 through 4.7. When checking Basic Authentication with HttpHeader::getAuth, Squid uses a global buffer to store the decoded data. Squid does not check that the decoded length isn't greater than the buffer, leading to a heap-based buffer overflow with user controlled data.

An issue was discovered in Squid 3.3.9 through 3.5.28 and 4.x through 4.7. When Squid is configured to use Digest authentication, it parses the header Proxy-Authorization. It searches for certain tokens such as domain, uri, and qop. Squid checks if this token's value starts with a quote and ends with one. If so, it performs a memcpy of its length minus 2. Squid never checks whether the value is just a single quote (which would satisfy its requirements), leading to a memcpy of its length minus 1.

An issue was discovered in Squid 2.x through 2.7.STABLE9, 3.x through 3.5.28, and 4.x through 4.7. When Squid is configured to use Basic Authentication, the Proxy-Authorization header is parsed via uudecode. uudecode determines how many bytes will be decoded by iterating over the input and checking its table. The length is then used to start decoding the string. There are no checks to ensure that the length it calculates isn't greater than the input buffer. This leads to adjacent memory being decoded as well. An attacker would not be able to retrieve the decoded data unless the Squid maintainer had configured the display of usernames on error pages.

log.c in Squid Analysis Report Generator (sarg) through 2.3.11 allows local privilege escalation. By default, it uses a fixed temporary directory /tmp/sarg. As the root user, sarg creates this directory or reuses an existing one in an insecure manner. An attacker can pre-create the directory, and place symlinks in it (after winning a /tmp/sarg/denied.int_unsort race condition). The outcome will be corrupted or newly created files in privileged file system locations.

The cachemgr.cgi web module of Squid through 4.7 has XSS via the user_name or auth parameter.

Squid before 4.4, when SNMP is enabled, allows a denial of service (Memory Leak) via an SNMP packet.

This vulnerability allows remote attackers to deny service on vulnerable installations of The Squid Software Foundation Squid 3.5.27-20180318. Authentication is not required to exploit this vulnerability. The specific flaw exists within ClientRequestContext::sslBumpAccessCheck(). A crafted request can trigger the dereference of a null pointer. An attacker can leverage this vulnerability to create a denial-of-service condition to users of the system. Was ZDI-CAN-6088.

The Squid Software Foundation Squid HTTP Caching Proxy version 3.0 to 3.5.27, 4.0 to 4.0.22 contains a Incorrect Pointer Handling vulnerability in ESI Response Processing that can result in Denial of Service for all clients using the proxy.. This attack appear to be exploitable via Remote server delivers an HTTP response payload containing valid but unusual ESI syntax.. This vulnerability appears to have been fixed in 4.0.23 and later.