Provide references for CVE-2017-18186.
Where can I find more information about CVE-2017-18186?
References are available at: https://usn.ubuntu.com/3638-1/, https://github.com/qpdf/qpdf/commit/85f05cc57ffa0a863d9d9b23e73acea9410b2937, https://github.com/qpdf/qpdf/issues/149.