The rfc1738doescape function in ftp.c for Squid 2.5 STABLE11 and earlier allows remote FTP servers to cause a denial of service (segmentation fault) via certain "odd" responses.

The sslConnectTimeout function in ssl.c for Squid 2.5.STABLE10 and earlier allows remote attackers to cause a denial of service (segmentation fault) via certain crafted requests.

store.c in Squid 2.5.STABLE10 and earlier allows remote attackers to cause a denial of service (crash) via certain aborted requests that trigger an assert error related to STOREPENDING.

Squid 2.5.STABLE7 and earlier allows remote attackers to cause a denial of service (segmentation fault) by aborting the connection during a (1) PUT or (2) POST request, which causes Squid to access previously freed memory.

Squid 2.5.STABLE8 and earlier allows remote attackers to cause a denial of service (crash) via certain DNS responses regarding (1) Fully Qualified Domain Names (FQDN) in fqdncache.c or (2) IP addresses in ipcache.c, which trigger an assertion failure.

squidldapauth in Squid 2.5 and earlier allows remote authenticated users to bypass username-based Access Control Lists (ACLs) via a username with a space at the beginning or end, which is ignored by the LDAP server.

Squid 2.5, when processing the configuration file, parses empty Access Control Lists (ACLs), including proxyauth ACLs without defined auth schemes, in a way that effectively removes arguments, which could allow remote attackers to bypass intended ACLs if the administrator ignores the parser warnings.