gnutls: unknown hash algorithm NULL pointer derefence [GNUTLS-SA-2006-2]

The gnutlsx509oid2macalgorithm function in lib/gnutlsalgorithms.c in GnuTLS before 1.4.2 allows remote attackers to cause a denial of service crash via a crafted X.509 certificate that uses a hash algorithm that is not supported by GnuTLS, which triggers a NULL pointer dereference...