The getFirstInTableInstance function in the IcedTea-Web plugin before 1.2.1 returns an uninitialized pointer when the instance_to_id_map hash is empty, which allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code via a crafted web page, which causes an uninitialized memory location to be read.
icedtea.classpath.org/hg/release/icedtea-web-1.2/file/icedtea-web-1.2.1/NEWS
lists.opensuse.org/opensuse-security-announce/2012-08/msg00003.html
lists.opensuse.org/opensuse-security-announce/2012-08/msg00004.html
lists.opensuse.org/opensuse-security-announce/2012-08/msg00005.html
lists.opensuse.org/opensuse-security-announce/2013-05/msg00020.html
lists.opensuse.org/opensuse-security-announce/2013-07/msg00013.html
lists.opensuse.org/opensuse-updates/2013-05/msg00032.html
lists.opensuse.org/opensuse-updates/2013-06/msg00030.html
lists.opensuse.org/opensuse-updates/2013-06/msg00101.html
rhn.redhat.com/errata/RHSA-2012-1132.html
secunia.com/advisories/50089
security.gentoo.org/glsa/glsa-201406-32.xml
www.ubuntu.com/usn/USN-1521-1
bugzilla.redhat.com/show_bug.cgi?id=840592