Integer underflow in the exif_entry_get_value function in exif-entry.c in the EXIF Tag Parsing Library (aka libexif) 0.6.20 might allow remote attackers to execute arbitrary code via vectors involving a crafted buffer-size parameter during the formatting of an EXIF tag, leading to a heap-based buffer overflow.
http://www.ubuntu.com/usn/USN-1513-1
http://www.securityfocus.com/bid/54437
http://www.debian.org/security/2012/dsa-2559
http://sourceforge.net/mailarchive/message.php?msg_id=29534027
http://secunia.com/advisories/49988
http://rhn.redhat.com/errata/RHSA-2012-1255.html
http://lists.opensuse.org/opensuse-security-announce/2012-07/msg00015.html
http://lists.opensuse.org/opensuse-security-announce/2012-07/msg00014.html