A resource leak in gw_backend.c in lighttpd 1.4.56 through 1.4.66 could lead to a denial of service (connection-slot exhaustion) after a large amount of anomalous TCP behavior by clients. It is related to RDHUP mishandling in certain HTTP/1.1 chunked situations. Use of mod_fastcgi is, for example, affected. This is fixed in 1.4.67.

Lighttpd 1.4.56 through 1.4.58 allows a remote attacker to cause a denial of service (CPU consumption from stuck connections) because connection_read_header_more in connections.c has a typo that disrupts use of multiple read operations on large headers.

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.