OpenVAS Manager 3.0 before 3.0.7 and 4.0 before 4.0.4 allows remote attackers to bypass the OMP authentication restrictions and execute OMP commands via a crafted OMP request for version information, which causes the state to be set to CLIENT_AUTHENTIC, as demonstrated by the omp_xml_handle_end_element function in omp.c.
http://www.openwall.com/lists/oss-security/2013/11/10/2
http://www.openvas.org/OVSA20131108.html
http://lists.wald.intevation.org/pipermail/openvas-announce/2013-November/000157.html