The buffer_urldecode function in Lighttpd 1.3.7 and earlier does not properly handle control characters, which allows remote attackers to obtain the source code for CGI and FastCGI scripts via a URL with a %00 (null) character after the file extension.

mod_userdir in lighttpd 1.4.18 and earlier, when userdir.path is not set, uses a default of $HOME, which might allow remote attackers to read arbitrary files, as demonstrated by accessing the ~nobody directory.

mod_cgi in lighttpd 1.4.18 sends the source code of CGI scripts instead of a 500 error when a fork failure occurs, which might allow remote attackers to obtain sensitive information.

Multiple directory traversal vulnerabilities in (1) mod_evhost and (2) mod_simple_vhost in lighttpd before 1.4.35 allow remote attackers to read arbitrary files via a .. (dot dot) in the host name, related to request_check_hostname.

An issue was discovered in mod_alias_physical_handler in mod_alias.c in lighttpd before 1.4.50. There is potential ../ path traversal of a single directory above an alias target, with a specific mod_alias configuration where the matched alias lacks a trailing '/' character, but the alias target filesystem path does have a trailing '/' character.