Index: yaml-cpp-0.5.1/src/singledocparser.cpp
===================================================================
--- yaml-cpp-0.5.1/src/singledocparser.cpp
+++ yaml-cpp-0.5.1/src/singledocparser.cpp	2018-11-19 21:05:08.826885213 +0100
@@ -12,7 +12,7 @@
 
 namespace YAML
 {
-	SingleDocParser::SingleDocParser(Scanner& scanner, const Directives& directives): m_scanner(scanner), m_directives(directives), m_pCollectionStack(new CollectionStack), m_curAnchor(0)
+	SingleDocParser::SingleDocParser(Scanner& scanner, const Directives& directives): depth(0), depth_limit(2048), m_scanner(scanner), m_directives(directives), m_pCollectionStack(new CollectionStack), m_curAnchor(0)
 	{
 	}
 
@@ -46,6 +46,10 @@
 	
 	void SingleDocParser::HandleNode(EventHandler& eventHandler)
 	{
+		if (depth > depth_limit) {
+			throw ParserException(m_scanner.mark(), ErrorMsg::BAD_FILE);
+		}
+
 		// an empty node *is* a possibility
 		if(m_scanner.empty()) {
 			eventHandler.OnNull(m_scanner.mark(), NullAnchor);
@@ -57,9 +61,11 @@
 		
 		// special case: a value node by itself must be a map, with no header
 		if(m_scanner.peek().type == Token::VALUE) {
+			depth++;
 			eventHandler.OnMapStart(mark, "?", NullAnchor);
 			HandleMap(eventHandler);
 			eventHandler.OnMapEnd();
+			depth--;
 			return;
 		}
 		
@@ -95,22 +101,28 @@
 				return;
 			case Token::FLOW_SEQ_START:
 			case Token::BLOCK_SEQ_START:
+				depth++;
 				eventHandler.OnSequenceStart(mark, tag, anchor);
 				HandleSequence(eventHandler);
 				eventHandler.OnSequenceEnd();
+				depth--;
 				return;
 			case Token::FLOW_MAP_START:
 			case Token::BLOCK_MAP_START:
+				depth++;
 				eventHandler.OnMapStart(mark, tag, anchor);
 				HandleMap(eventHandler);
 				eventHandler.OnMapEnd();
+				depth--;
 				return;
 			case Token::KEY:
 				// compact maps can only go in a flow sequence
 				if(m_pCollectionStack->GetCurCollectionType() == CollectionType::FlowSeq) {
+					depth++;
 					eventHandler.OnMapStart(mark, tag, anchor);
 					HandleMap(eventHandler);
 					eventHandler.OnMapEnd();
+					depth--;
 					return;
 				}
 				break;
Index: yaml-cpp-0.5.1/src/singledocparser.h
===================================================================
--- yaml-cpp-0.5.1/src/singledocparser.h
+++ yaml-cpp-0.5.1/src/singledocparser.h	2018-11-19 21:04:44.364042993 +0100
@@ -51,6 +51,8 @@
 		anchor_t LookupAnchor(const Mark& mark, const std::string& name) const;
 		
 	private:
+		int depth;
+		int depth_limit;
 		Scanner& m_scanner;
 		const Directives& m_directives;
 		std::auto_ptr<CollectionStack> m_pCollectionStack;