The RuntimeHelpers.InitializeArray method in metadata/icall.c in Mono, when Moonlight 2.x before 2.4.1 or 3.x before 3.99.3 is used, does not properly restrict data types, which allows remote attackers to modify internal read-only data structures, and cause a denial of service (plugin crash) or corrupt the internal state of the security manager, via a crafted media file, as demonstrated by modifying a C# struct.
lists.opensuse.org/opensuse-updates/2011-04/msg00024.html
openwall.com/lists/oss-security/2011/04/06/14
secunia.com/advisories/44002
secunia.com/advisories/44076
www.mono-project.com/Vulnerabilities
www.securityfocus.com/bid/47208
www.vupen.com/english/advisories/2011/0904
bugzilla.novell.com/show_bug.cgi?id=667077
exchange.xforce.ibmcloud.com/vulnerabilities/66624
github.com/mono/mono/commit/035c8587c0d8d307e45f1b7171a0d337bb451f1e