The updated packages fix security vulnerabilities:
The FoFiType1C::cvtGlyph function in fofi/FoFiType1C.cc in Poppler through 0.64.0 allows remote attackers to cause a denial of service (infinite recursion) via a crafted PDF file, as demonstrated by pdftops. (CVE-2017-18267)
There is a NULL pointer dereference in the AnnotPath::getCoordsLength function in Annot.h in an Ubuntu package for Poppler 0.24.5. A crafted input will lead to a remote denial of service attack. Later Ubuntu packages such as for Poppler 0.41.0 are not affected. (CVE-2018-10768)