Squid security advisory 2016:3 reports:
Due to a buffer overrun Squid pinger binary is vulnerable to
denial of service or information leak attack when processing
ICMPv6 packets.
This bug also permits the server response to manipulate other
ICMP and ICMPv6 queries processing to cause information leak.
This bug allows any remote server to perform a denial of service
attack on the Squid service by crashing the pinger. This may
affect Squid HTTP routing decisions. In some configurations,
sub-optimal routing decisions may result in serious service
degradation or even transaction failures.
If the system does not contain buffer-overrun protection leading
to that crash this bug will instead allow attackers to leak
arbitrary amounts of information from the heap into Squid log
files. This is of higher importance than usual because the pinger
process operates with root priviliges.
Squid security advisory 2016:4 reports:
Due to incorrect bounds checking Squid is vulnerable to a denial
of service attack when processing HTTP responses.
This problem allows a malicious client script and remote server
delivering certain unusual HTTP response syntax to trigger a
denial of service for all clients accessing the Squid service.