Apache 1.3 through 1.3.24, and Apache 2.0 through 2.0.36, allows remote attackers to cause a denial of service and possibly execute arbitrary code via a chunk-encoded HTTP request that causes Apache to use an incorrect size.
Apache for Win32 before 1.3.24, and 2.0.x before 2.0.34-beta, allows remote attackers to execute arbitrary commands via shell metacharacters (a | pipe character) provided as arguments to batch (.bat) or .cmd scripts, which are sent unfiltered to the shell interpreter, typically cmd.exe.
The log files in Apache web server contain information directly supplied by clients and does not filter or quote control characters, which could allow remote attackers to hide HTTP requests and spoof source IP addresses when logs are viewed with UNIX programs such as cat, tail, and grep.