Squid is a caching proxy for the Web. Prior to 7.6, due to an improper input validation bug in cache digest reply handling (peerDigestSwapInMask in src/peer_digest.cc), Squid is vulnerable to a heap-based buffer overflow: a cache digest's on-the-wire size may be larger than the mask_size declared within the digest, so a trusted peer sending a maliciously crafted reply to a cache_digest request message can trigger the overflow. This attack is limited to Squid instances compiled with the --enable-cache-digests option and configured with cache_peer entries. This issue is fixed in version 7.6.

Squid is a caching proxy for the Web. Prior to 7.6, due to an improper validation of syntactic correctness of input in the FTP gateway (src/clients/FtpGateway.cc), Squid is vulnerable to an out-of-bounds read: when a listing entry date in the TypeA or TypeB directory-listing formats is not followed by a filename, parsing was not restricted to the input buffer, so a trusted client accessing a misbehaving FTP server through Squid's gateway feature could read memory from random unrelated transactions. This issue is fixed in version 7.6.

Squid is a caching proxy for the Web. Prior to version 7.5, due to heap Use-After-Free, Squid is vulnerable to Denial of Service when handling ICP traffic. This problem allows a remote attacker to perform a reliable and repeatable Denial of Service attack against the Squid service using ICP protocol. This attack is limited to Squid deployments that explicitly enable ICP support (i.e. configure non-zero `icp_port`). This problem _cannot_ be mitigated by denying ICP queries using `icp_access` rules. Version 7.5 contains a patch.

Squid is a caching proxy for the Web. Prior to version 7.5, due to improper input validation, Squid is vulnerable to out of bounds read when handling ICP traffic. This problem allows a remote attacker to receive small amounts of memory potentially containing sensitive information when responding with errors to invalid ICP requests. This attack is limited to Squid deployments that explicitly enable ICP support (i.e. configure non-zero `icp_port`). This problem cannot be mitigated by denying ICP queries using `icp_access` rules. Version 7.5 contains a patch.

Squid is a caching proxy for the Web. Prior to version 7.5, due to premature release of resource during expected lifetime and heap Use-After-Free bugs, Squid is vulnerable to Denial of Service when handling ICP traffic. This problem allows a remote attacker to perform a reliable and repeatable Denial of Service attack against the Squid service using ICP protocol. This attack is limited to Squid deployments that explicitly enable ICP support (i.e. configure non-zero `icp_port`). This problem _cannot_ be mitigated by denying ICP queries using `icp_access` rules. This bug is fixed in Squid version 7.5.

Squid is a caching proxy for the Web. In Squid versions prior to 7.2, a failure to redact HTTP authentication credentials in error handling allows information disclosure. The vulnerability allows a script to bypass browser security protections and learn the credentials a trusted client uses to authenticate. This potentially allows a remote client to identify security tokens or credentials used internally by a web application using Squid for backend load balancing. These attacks do not require Squid to be configured with HTTP authentication. The vulnerability is fixed in version 7.2. As a workaround, disable debug information in administrator mailto links generated by Squid by configuring squid.conf with email_err_data off.

Squid through 7.1 mishandles ASN.1 encoding of long SNMP OIDs. This occurs in asn_build_objid in lib/snmplib/asn1.c.