freexl is susceptible to denial of service(DoS). The attack can launched by sending a malicious file to destroy_cell()
function, leading to heap-based buffer over-read.
bugzilla.redhat.com/show_bug.cgi?id=1547879
bugzilla.redhat.com/show_bug.cgi?id=1549720
groups.google.com/forum/#!topic/spatialite-users/b-d9iB5TDPE
lists.debian.org/debian-lts-announce/2018/03/msg00000.html
security.gentoo.org/glsa/202007-44
www.debian.org/security/2018/dsa-4129
www.gaia-gis.it/fossil/freexl/fdiff?v1=22c434256e49fa28&v2=7d9366ce45f1ff18&sbs=1
www.gaia-gis.it/fossil/freexl/fdiff?v1=7d9366ce45f1ff18&v2=b206d5fedf9b48aa&sbs=1