lighttpd before 1.4.54 has a signed integer overflow, which might allow remote attackers to cause a denial of service (application crash) or possibly have unspecified other impact via a malicious HTTP GET request, as demonstrated by mishandling of /%2F? in burl_normalize_2F_to_slash_fix in burl.c. NOTE: The developer states "The feature which can be abused to cause the crash is a new feature in lighttpd 1.4.50, and is not enabled by default. It must be explicitly configured in the config file (e.g. lighttpd.conf). Certain input will trigger an abort() in lighttpd when that feature is enabled. lighttpd detects the underflow or realloc() will fail (in both 32-bit and 64-bit executables), also detected in lighttpd. Either triggers an explicit abort() by lighttpd. This is not exploitable beyond triggering the explicit abort() with subsequent application exit.

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.

mod_auth in lighttpd before 1.4.36 allows remote attackers to inject arbitrary log entries via a basic HTTP authentication string without a colon character, as demonstrated by a string containing a NULL and new line character.

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.

SQL injection vulnerability in mod_mysql_vhost.c in lighttpd before 1.4.35 allows remote attackers to execute arbitrary SQL commands via the host name, related to request_check_hostname.

lighttpd before 1.4.33 does not check the return value of the (1) setuid, (2) setgid, or (3) setgroups functions, which might cause lighttpd to run as root if it is restarted and allows remote attackers to gain privileges, as demonstrated by multiple calls to the clone function that cause setuid to fail when the user process limit is reached.

Use-after-free vulnerability in lighttpd before 1.4.33 allows remote attackers to cause a denial of service (segmentation fault and crash) via unspecified vectors that trigger FAMMonitorDirectory failures.

The configuration file for the FastCGI PHP support for lighttpd before 1.4.28 on Debian GNU/Linux creates a socket file with a predictable name in /tmp, which allows local users to hijack the PHP control socket and perform unauthorized actions such as forcing the use of a different version of PHP via a symlink attack or a race condition.

Integer signedness error in the base64_decode function in the HTTP authentication functionality (http_auth.c) in lighttpd 1.4 before 1.4.30 and 1.5 before SVN revision 2806 allows remote attackers to cause a denial of service (segmentation fault) via crafted base64 input that triggers an out-of-bounds read with a negative index.

lighttpd before 1.4.26, and 1.5.x, allocates a buffer for each read operation that occurs for a request, which allows remote attackers to cause a denial of service (memory consumption) by breaking a request into small pieces that are sent at a slow rate.

mod_userdir in lighttpd before 1.4.20, when a case-insensitive operating system or filesystem is used, performs case-sensitive comparisons on filename components in configuration options, which might allow remote attackers to bypass intended access restrictions, as demonstrated by a request for a .PHP file when there is a configuration rule for .php files.

lighttpd before 1.4.20 compares URIs to patterns in the (1) url.redirect and (2) url.rewrite configuration settings before performing URL decoding, which might allow remote attackers to bypass intended access restrictions, and obtain sensitive information or possibly modify data.

Memory leak in the http_request_parse function in request.c in lighttpd before 1.4.20 allows remote attackers to cause a denial of service (memory consumption) via a large number of requests with duplicate request headers.

The connection_state_machine function (connections.c) in lighttpd 1.4.19 and earlier, and 1.5.x before 1.5.0, allows remote attackers to cause a denial of service (active SSL connection loss) by triggering an SSL error, such as disconnecting before a download has finished, which causes all active SSL connections to be lost.

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.

lighttpd 1.4.18, and possibly other versions before 1.5.0, does not properly calculate the size of a file descriptor array, which allows remote attackers to cause a denial of service (crash) via a large number of connections, which triggers an out-of-bounds access.

Buffer overflow in the fcgi_env_add function in mod_proxy_backend_fastcgi.c in the mod_fastcgi extension in lighttpd before 1.4.18 allows remote attackers to overwrite arbitrary CGI variables and execute arbitrary code via an HTTP request with a long content length, as demonstrated by overwriting the SCRIPT_FILENAME variable, aka a "header overflow."

mod_auth (http_auth.c) in lighttpd before 1.4.16 allows remote attackers to cause a denial of service (daemon crash) via unspecified vectors involving (1) a memory leak, (2) use of md5-sess without a cnonce, (3) base64 encoded strings, and (4) trailing whitespace in the Auth-Digest header.

request.c in lighttpd 1.4.15 allows remote attackers to cause a denial of service (daemon crash) by sending an HTTP request with duplicate headers, as demonstrated by a request containing two Location header lines, which results in a segmentation fault.

connections.c in lighttpd before 1.4.16 might accept more connections than the configured maximum, which allows remote attackers to cause a denial of service (failed assertion) via a large number of connection attempts.