diff --git a/Tests/Fuzzers/CMakeLists.txt b/Tests/Fuzzers/CMakeLists.txt
index c22c13be65..b871929a4c 100644
--- a/Tests/Fuzzers/CMakeLists.txt
+++ b/Tests/Fuzzers/CMakeLists.txt
@@ -20,3 +20,7 @@ target_compile_definitions(FuzzWriter PUBLIC FILE_EXT=".pcap" NG_WRITER)
 add_executable(FuzzWriterNg FuzzWriter.cpp)
 target_link_libraries(FuzzWriterNg PRIVATE Pcap++ -fsanitize=fuzzer)
 target_compile_definitions(FuzzWriterNg PUBLIC FILE_EXT=".pcapng")
+
+add_executable(FuzzX509 FuzzX509.cpp)
+target_link_libraries(FuzzX509 PRIVATE Pcap++ -fsanitize=fuzzer)
+target_include_directories(FuzzX509 PRIVATE $<TARGET_PROPERTY:EndianPortable,INTERFACE_INCLUDE_DIRECTORIES>)
diff --git a/Tests/Fuzzers/FuzzX509.cpp b/Tests/Fuzzers/FuzzX509.cpp
new file mode 100644
index 0000000000..18f2c1fd0d
--- /dev/null
+++ b/Tests/Fuzzers/FuzzX509.cpp
@@ -0,0 +1,84 @@
+#include <cstdint>
+#include <memory>
+#include <vector>
+
+#include <X509Decoder.h>
+#include <X509ExtensionDataDecoder.h>
+#include <Logger.h>
+
+extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size)
+{
+	if (size == 0)
+		return 0;
+
+	pcpp::Logger::getInstance().suppressLogs();
+
+	// fromDER needs a mutable buffer that outlives the parse
+	std::vector<uint8_t> buf(data, data + size);
+
+	try
+	{
+		auto cert = pcpp::X509Certificate::fromDER(buf.data(), buf.size());
+		if (!cert)
+			return 0;
+
+		cert->getVersion();
+		cert->getSerialNumber();
+		cert->getIssuer();
+		cert->getSubject();
+		cert->getNotBefore();
+		cert->getNotAfter();
+		cert->getPublicKeyAlgorithm();
+		cert->getPublicKey();
+		cert->getSignatureAlgorithm();
+		cert->getSignature();
+		cert->toJson();
+
+		for (const auto& ext : cert->getExtensions())
+		{
+			ext.getType();
+			ext.isCritical();
+
+			auto extData = ext.getData();
+			if (!extData)
+				continue;
+
+			switch (ext.getType())
+			{
+			case pcpp::X509ExtensionType::BasicConstraints:
+			{
+				auto* bc = extData->castAs<pcpp::X509BasicConstraintsExtension>();
+				bc->isCA();
+				bc->getPathLenConstraint();
+				break;
+			}
+			case pcpp::X509ExtensionType::KeyUsage:
+			{
+				auto* ku = extData->castAs<pcpp::X509KeyUsageExtension>();
+				ku->isDigitalSignature();
+				ku->isNonRepudiation();
+				ku->isKeyEncipherment();
+				ku->isDataEncipherment();
+				ku->isKeyAgreement();
+				ku->isKeyCertSign();
+				ku->isCRLSign();
+				ku->isEncipherOnly();
+				ku->isDecipherOnly();
+				break;
+			}
+			case pcpp::X509ExtensionType::ExtendedKeyUsage:
+				extData->castAs<pcpp::X509ExtendedKeyUsageExtension>()->getPurposes();
+				break;
+			case pcpp::X509ExtensionType::SubjectKeyIdentifier:
+				extData->castAs<pcpp::X509SubjectKeyIdentifierExtension>()->getKeyIdentifier();
+				break;
+			default:
+				break;
+			}
+		}
+	}
+	catch (...)
+	{}
+
+	return 0;
+}
diff --git a/Tests/Fuzzers/ossfuzz.sh b/Tests/Fuzzers/ossfuzz.sh
index 6d461ff649..7915257f10 100755
--- a/Tests/Fuzzers/ossfuzz.sh
+++ b/Tests/Fuzzers/ossfuzz.sh
@@ -20,7 +20,8 @@ FUZZERS="FuzzTarget \
     FuzzTargetNg \
     FuzzTargetSnoop \
     FuzzWriter \
-    FuzzWriterNg"
+    FuzzWriterNg \
+    FuzzX509"
 
 for fuzzer in $FUZZERS; do
     cp $TARGETS_DIR/Tests/Fuzzers/${fuzzer} $OUT
@@ -34,3 +35,4 @@ find $SRC/ -iname "*.pcapng" | xargs zip $OUT/FuzzTargetNg_seed_corpus.zip
 find $SRC/ -iname "*.snoop"  | xargs zip $OUT/FuzzTargetSnoop_seed_corpus.zip
 find $SRC/ -iname "*.pcap"   | xargs zip $OUT/FuzzWriter_seed_corpus.zip
 find $SRC/ -iname "*.pcapng" | xargs zip $OUT/FuzzWriterNg_seed_corpus.zip
+find $SRC/ -iname "*.der"    | xargs zip $OUT/FuzzX509_seed_corpus.zip