mod_usertrack in Apache 1.3.11 through 1.3.20 generates session ID's using predictable information including host IP address, system time and server process ID, which allows local users to obtain session ID's and bypass authentication when these session ID's are used for authentication.

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.

Apache 1.3.20 on Windows servers allows remote attackers to bypass the default index page and list directory contents via a URL with a large number of / (slash) characters.

split-logfile in Apache 1.3.20 allows remote attackers to overwrite arbitrary files that end in the .log extension via an HTTP request with a / (slash) in the Host: header.

Apache 1.3.20 with Multiviews enabled allows remote attackers to view directory contents and bypass the index page via a URL containing the "M=D" query string.