SquidGuard website reports:
Patch 20091015 fixes one buffer overflow problem in sgLog.c when overlong URLs are requested. SquidGuard will then go into emergency mode were no blocking occurs. This is not required in this situation.
Patch 20091019 fixes two bypass problems with URLs which length is close to the limit defined by MAX_BUF (default: 4096) in squidGuard and MAX_URL (default: 4096 in squid 2.x and 8192 in squid 3.x) in squid. For this kind of URLs the proxy request exceeds MAX_BUF causing squidGuard to complain about not being able to parse the squid request. Increasing the buffer limit to be higher than the one defined in MAX_URL solves the issue.