The wmem_block_split_free_chunk function in epan/wmem/wmem_allocator_block.c in the wmem block allocator in the memory manager in Wireshark 1.12.x before 1.12.7 does not properly consider a certain case of multiple realloc operations that restore a memory chunk to its original size, which allows remote attackers to cause a denial of service (incorrect free operation and application crash) via a crafted packet.
https://bugs.wireshark.org/bugzilla/show_bug.cgi?id=11373
http://www.wireshark.org/security/wnpa-sec-2015-22.html
http://www.securitytracker.com/id/1033272
http://www.oracle.com/technetwork/topics/security/bulletinoct2015-2511968.html
http://www.debian.org/security/2015/dsa-3367
http://lists.opensuse.org/opensuse-updates/2015-10/msg00053.html
http://lists.fedoraproject.org/pipermail/package-announce/2015-September/165509.html
http://lists.fedoraproject.org/pipermail/package-announce/2015-October/168837.html