1 files changed, 2 insertions, 1 deletions
diff --git a/core/fpdfapi/parser/cpdf_data_avail.cpp b/core/fpdfapi/parser/cpdf_data_avail.cpp
index 76190fa9a9..b7ea238507 100644
--- a/core/fpdfapi/parser/cpdf_data_avail.cpp
+++ b/core/fpdfapi/parser/cpdf_data_avail.cpp
@@ -943,8 +943,9 @@ bool CPDF_DataAvail::CheckTrailer() {
     return true;
   }
 
+  // Prevent infinite-looping between Prev entries.
   uint32_t xrefpos = GetDirectInteger(pTrailerDict, "Prev");
-  if (!xrefpos) {
+  if (!xrefpos || !m_SeenPrevPositions.insert(xrefpos).second) {
     m_dwPrevXRefOffset = 0;
     m_docStatus = PDF_DATAAVAIL_LOADALLCROSSREF;
     return true;