In lighttpd 1.4.46 through 1.4.63, the mod_extforward_Forwarded function of the mod_extforward plugin has a stack-based buffer overflow (4 bytes representing -1), as demonstrated by remote denial of service (daemon crash) in a non-default configuration. The non-default configuration requires handling of the Forwarded header in a somewhat unusual manner. Also, a 32-bit system is much more likely to be affected than a 64-bit system.

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.

lighttpd 1.4.15, when run on 32 bit platforms, allows remote attackers to cause a denial of service (daemon crash) via unspecified vectors involving the use of incompatible format specifiers in certain debugging messages in the (1) mod_scgi, (2) mod_fastcgi, and (3) mod_webdav modules.