In QPDF 8.2.1, in libqpdf/QPDFWriter.cc, QPDFWriter::unparseObject and QPDFWriter::unparseChild have recursive calls for a long time, which allows remote attackers to cause a denial of service via a crafted PDF file.
Exploitability
AV:LAC:LPR:NUI:RScope
S:UImpact
C:NI:NA:L3.3/CVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L