diff -up qpdf-6.0.0/include/qpdf/QPDF.hh.CVE-2017-9209 qpdf-6.0.0/include/qpdf/QPDF.hh
--- qpdf-6.0.0/include/qpdf/QPDF.hh.CVE-2017-9209	2017-08-03 10:00:17.489291722 +0200
+++ qpdf-6.0.0/include/qpdf/QPDF.hh	2017-08-03 10:00:17.494291685 +0200
@@ -1095,6 +1095,7 @@ class QPDF
     // copied_stream_data_provider is owned by copied_streams
     CopiedStreamDataProvider* copied_stream_data_provider;
     std::set<QPDFObjGen> attachment_streams;
+    bool reconstructed_xref;    
 
     // Linearization data
     qpdf_offset_t first_xref_item_offset; // actual value from file
diff -up qpdf-6.0.0/libqpdf/QPDF.cc.CVE-2017-9209 qpdf-6.0.0/libqpdf/QPDF.cc
--- qpdf-6.0.0/libqpdf/QPDF.cc.CVE-2017-9209	2017-08-03 10:00:17.491291707 +0200
+++ qpdf-6.0.0/libqpdf/QPDF.cc	2017-08-03 10:01:43.243661883 +0200
@@ -93,6 +93,7 @@ QPDF::QPDF() :
     cached_key_generation(0),
     pushed_inherited_attributes_to_pages(false),
     copied_stream_data_provider(0),
+    reconstructed_xref(false),
     first_xref_item_offset(0),
     uncompressed_after_compressed(false)
 {
@@ -331,6 +332,14 @@ QPDF::setTrailer(QPDFObjectHandle obj)
 void
 QPDF::reconstruct_xref(QPDFExc& e)
 {
+    if (this->reconstructed_xref)
+    {
+        // Avoid xref reconstruction infinite loops
+        throw e;
+    }
+
+    this->reconstructed_xref = true;
+
     PCRE obj_re("^\\s*(\\d+)\\s+(\\d+)\\s+obj\\b");
     PCRE endobj_re("^\\s*endobj\\b");
     PCRE trailer_re("^\\s*trailer\\b");