The function Object::isName() in Object.h (called from Gfx::opSetFillColorN) in Xpdf 4.00 allows remote attackers to cause a denial of service (stack-based buffer over-read) via a crafted pdf file, as demonstrated by pdftoppm.
https://github.com/TeamSeri0us/pocs/tree/master/xpdf/2018_10_16/pdftoppm