libqpdf.a in QPDF through 8.0.2 mishandles certain "expected dictionary key but found non-name object" cases, allowing remote attackers to cause a denial of service (stack exhaustion), related to the QPDFObjectHandle and QPDF_Dictionary classes, because nesting in direct objects is not restricted.
An issue was discovered in QPDF before 7.0.0. Endless recursion causes stack exhaustion in QPDFTokenizer::resolveLiteral() in QPDFTokenizer.cc, related to the QPDF::resolve function in QPDF.cc.
An issue was discovered in QPDF before 7.0.0. There is a large heap-based out-of-bounds read in the Pl_Buffer::write function in Pl_Buffer.cc. It is caused by an integer overflow in the PNG filter.