The qcow2_open function in the (block/qcow2.c) in QEMU before 1.7.2 and 2.x before 2.0.0 allows local users to cause a denial of service (NULL pointer dereference) via a crafted image which causes an error, related to the initialization of the snapshot_offset and nb_snapshots fields.
https://bugzilla.redhat.com/show_bug.cgi?id=1078232
http://www.openwall.com/lists/oss-security/2014/03/26/8
http://www.debian.org/security/2014/dsa-3044
http://rhn.redhat.com/errata/RHSA-2014-0421.html
http://rhn.redhat.com/errata/RHSA-2014-0420.html
http://git.qemu.org/?p=qemu.git%3Ba=commit%3Bh=11b128f4062dd7f89b14abc8877ff20d41b28be9