irc_server.c in dircproxy 1.2.0 and earlier allows remote attackers to cause a denial of service (segmentation fault) via an ACTION command without a parameter, which triggers a NULL pointer dereference, as demonstrated using a blank /me message from irssi.
The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.