The function "Token& Scanner::peek" in scanner.cpp in yaml-cpp 0.5.3 and earlier allows remote attackers to cause a denial of service (assertion failure and application exit) via a '!2' string.
The SingleDocParser::HandleNode function in yaml-cpp (aka LibYaml-C++) 0.5.3 allows remote attackers to cause a denial of service (stack consumption and application crash) via a crafted YAML file.