diff --git a/core/bind/core_bind.cpp b/core/bind/core_bind.cpp
index 0b2b59dc87..2121703b32 100644
--- a/core/bind/core_bind.cpp
+++ b/core/bind/core_bind.cpp
@@ -2467,6 +2467,8 @@ void _Directory::_bind_methods() {
 
 _Directory::_Directory() {
 	d = DirAccess::create(DirAccess::ACCESS_RESOURCES);
+	_list_skip_navigational = false;
+	_list_skip_hidden = false;
 }
 
 _Directory::~_Directory() {
diff --git a/core/class_db.cpp b/core/class_db.cpp
index 269ec667c0..fa5433bd06 100644
--- a/core/class_db.cpp
+++ b/core/class_db.cpp
@@ -248,6 +248,7 @@ ClassDB::ClassInfo::ClassInfo() {
 	inherits_ptr = nullptr;
 	disabled = false;
 	exposed = false;
+	class_ptr = nullptr;
 }
 
 ClassDB::ClassInfo::~ClassInfo() {
diff --git a/core/crypto/hashing_context.cpp b/core/crypto/hashing_context.cpp
index bd55b03779..2c723bbcc4 100644
--- a/core/crypto/hashing_context.cpp
+++ b/core/crypto/hashing_context.cpp
@@ -129,6 +129,7 @@ void HashingContext::_bind_methods() {
 
 HashingContext::HashingContext() {
 	ctx = nullptr;
+	type = HashType::HASH_MD5;
 }
 
 HashingContext::~HashingContext() {
diff --git a/core/engine.cpp b/core/engine.cpp
index b6af54877b..367729c927 100644
--- a/core/engine.cpp
+++ b/core/engine.cpp
@@ -237,6 +237,7 @@ Engine::Engine() {
 	_frame_step = 0;
 	editor_hint = false;
 	_portals_active = false;
+	_occlusion_culling_active = false;
 }
 
 Engine::Singleton::Singleton(const StringName &p_name, Object *p_ptr) :
diff --git a/core/io/file_access_compressed.cpp b/core/io/file_access_compressed.cpp
index a7a6ae493b..1a640af9f8 100644
--- a/core/io/file_access_compressed.cpp
+++ b/core/io/file_access_compressed.cpp
@@ -375,6 +375,7 @@ Error FileAccessCompressed::_set_unix_permissions(const String &p_file, uint32_t
 FileAccessCompressed::FileAccessCompressed() :
 		cmode(Compression::MODE_ZSTD),
 		writing(false),
+		write_pos(0),
 		write_ptr(nullptr),
 		write_buffer_size(0),
 		write_max(0),
diff --git a/core/io/file_access_encrypted.cpp b/core/io/file_access_encrypted.cpp
index a0c534b472..4a3834036f 100644
--- a/core/io/file_access_encrypted.cpp
+++ b/core/io/file_access_encrypted.cpp
@@ -296,6 +296,8 @@ Error FileAccessEncrypted::_set_unix_permissions(const String &p_file, uint32_t
 
 FileAccessEncrypted::FileAccessEncrypted() {
 	file = nullptr;
+	base = 0;
+	length = 0;
 	pos = 0;
 	eofed = false;
 	mode = MODE_MAX;
diff --git a/core/io/file_access_memory.cpp b/core/io/file_access_memory.cpp
index 7e8823552a..8fb5652807 100644
--- a/core/io/file_access_memory.cpp
+++ b/core/io/file_access_memory.cpp
@@ -181,4 +181,6 @@ void FileAccessMemory::store_buffer(const uint8_t *p_src, uint64_t p_length) {
 
 FileAccessMemory::FileAccessMemory() {
 	data = nullptr;
+	length = 0;
+	pos = 0;
 }
diff --git a/core/io/http_client.cpp b/core/io/http_client.cpp
index e30b59a6fd..68ea9c92e2 100644
--- a/core/io/http_client.cpp
+++ b/core/io/http_client.cpp
@@ -764,6 +764,7 @@ HTTPClient::HTTPClient() {
 	chunk_trailer_part = false;
 	response_num = 0;
 	ssl = false;
+	ssl_verify_host = false;
 	blocking = false;
 	handshaking = false;
 	// 64 KiB by default (favors fast download speeds at the cost of memory usage).
diff --git a/core/io/packet_peer_udp.cpp b/core/io/packet_peer_udp.cpp
index fb014094f1..637923d46d 100644
--- a/core/io/packet_peer_udp.cpp
+++ b/core/io/packet_peer_udp.cpp
@@ -359,6 +359,8 @@ PacketPeerUDP::PacketPeerUDP() :
 		udp_server(nullptr),
 		_sock(Ref<NetSocket>(NetSocket::create())) {
 	rb.resize(16);
+	memset(recv_buffer, 0, sizeof(recv_buffer));
+	memset(packet_buffer, 0, sizeof(packet_buffer));
 }
 
 PacketPeerUDP::~PacketPeerUDP() {
diff --git a/core/io/pck_packer.cpp b/core/io/pck_packer.cpp
index ffb4eeb1df..5883141b3c 100644
--- a/core/io/pck_packer.cpp
+++ b/core/io/pck_packer.cpp
@@ -174,6 +174,7 @@ Error PCKPacker::flush(bool p_verbose) {
 
 PCKPacker::PCKPacker() {
 	file = nullptr;
+	alignment = 0;
 };
 
 PCKPacker::~PCKPacker() {
diff --git a/core/io/resource_format_binary.cpp b/core/io/resource_format_binary.cpp
index 86c8904d14..2602312047 100644
--- a/core/io/resource_format_binary.cpp
+++ b/core/io/resource_format_binary.cpp
@@ -917,7 +917,9 @@ String ResourceInteractiveLoaderBinary::recognize(FileAccess *p_f) {
 
 ResourceInteractiveLoaderBinary::ResourceInteractiveLoaderBinary() :
 		translation_remapped(false),
+		ver_format(0),
 		f(nullptr),
+		importmd_ofs(0),
 		error(OK),
 		stage(0) {
 }
diff --git a/core/io/udp_server.cpp b/core/io/udp_server.cpp
index f56fb431ef..4a586a6e54 100644
--- a/core/io/udp_server.cpp
+++ b/core/io/udp_server.cpp
@@ -195,6 +195,7 @@ void UDPServer::stop() {
 
 UDPServer::UDPServer() :
 		_sock(Ref<NetSocket>(NetSocket::create())) {
+	memset(recv_buffer, 0, sizeof(recv_buffer));
 }
 
 UDPServer::~UDPServer() {
diff --git a/core/math/a_star.h b/core/math/a_star.h
index 4606ee1a24..23220501ce 100644
--- a/core/math/a_star.h
+++ b/core/math/a_star.h
@@ -46,8 +46,12 @@ class AStar : public Reference {
 
 	struct Point {
 		Point() :
+				id(0),
+				enabled(false),
 				neighbours(4u),
-				unlinked_neighbours(4u) {}
+				unlinked_neighbours(4u),
+				prev_point(nullptr),
+				open_pass(0) {}
 
 		int id;
 		Vector3 pos;
diff --git a/core/math/expression.cpp b/core/math/expression.cpp
index 17f223cd9d..02d9029203 100644
--- a/core/math/expression.cpp
+++ b/core/math/expression.cpp
@@ -2188,6 +2188,8 @@ void Expression::_bind_methods() {
 Expression::Expression() :
 		output_type(Variant::NIL),
 		sequenced(false),
+		str_ofs(0),
+		expression_dirty(false),
 		error_set(true),
 		root(nullptr),
 		nodes(nullptr),
diff --git a/core/math/expression.h b/core/math/expression.h
index 2e76fa06c5..7f69beb460 100644
--- a/core/math/expression.h
+++ b/core/math/expression.h
@@ -218,7 +218,10 @@ private:
 
 		Type type;
 
-		ENode() { next = nullptr; }
+		ENode() {
+			type = Type::TYPE_INPUT;
+			next = nullptr;
+		}
 		virtual ~ENode() {
 			if (next) {
 				memdelete(next);
@@ -240,6 +243,7 @@ private:
 		int index;
 		InputNode() {
 			type = TYPE_INPUT;
+			index = 0;
 		}
 	};
 
@@ -257,6 +261,8 @@ private:
 
 		OperatorNode() {
 			type = TYPE_OPERATOR;
+			nodes[0] = nullptr;
+			nodes[1] = nullptr;
 		}
 	};
 
@@ -272,6 +278,8 @@ private:
 
 		IndexNode() {
 			type = TYPE_INDEX;
+			base = nullptr;
+			index = nullptr;
 		}
 	};
 
@@ -281,6 +289,7 @@ private:
 
 		NamedIndexNode() {
 			type = TYPE_NAMED_INDEX;
+			base = nullptr;
 		}
 	};
 
@@ -300,6 +309,7 @@ private:
 
 		CallNode() {
 			type = TYPE_CALL;
+			base = nullptr;
 		}
 	};
 
@@ -322,6 +332,7 @@ private:
 		Vector<ENode *> arguments;
 		BuiltinFuncNode() {
 			type = TYPE_BUILTIN_FUNC;
+			func = BuiltinFunc::MATH_SIN;
 		}
 	};
 
diff --git a/core/object.h b/core/object.h
index 220fa645d2..17fedb1c91 100644
--- a/core/object.h
+++ b/core/object.h
@@ -457,7 +457,10 @@ private:
 			int reference_count;
 			Connection conn;
 			List<Connection>::Element *cE;
-			Slot() { reference_count = 0; }
+			Slot() {
+				reference_count = 0;
+				cE = nullptr;
+			}
 		};
 
 		MethodInfo user;
diff --git a/core/os/dir_access.cpp b/core/os/dir_access.cpp
index ad0be6cbf2..f95e565175 100644
--- a/core/os/dir_access.cpp
+++ b/core/os/dir_access.cpp
@@ -422,6 +422,7 @@ bool DirAccess::exists(String p_dir) {
 
 DirAccess::DirAccess() {
 	_access_type = ACCESS_FILESYSTEM;
+	next_is_dir = false;
 }
 
 DirAccess::~DirAccess() {
diff --git a/core/os/file_access.cpp b/core/os/file_access.cpp
index a362d0f72b..dac0e78dbf 100644
--- a/core/os/file_access.cpp
+++ b/core/os/file_access.cpp
@@ -280,6 +280,7 @@ public:
 			buffer(stack_buffer),
 			capacity(sizeof(stack_buffer) / sizeof(char)),
 			written(0) {
+		memset(stack_buffer, 0, sizeof(stack_buffer));
 	}
 
 	_FORCE_INLINE_ void push_back(char c) {
diff --git a/core/packed_data_container.cpp b/core/packed_data_container.cpp
index 7be91c6c23..3869a80fdb 100644
--- a/core/packed_data_container.cpp
+++ b/core/packed_data_container.cpp
@@ -396,4 +396,5 @@ int PackedDataContainerRef::size() const {
 };
 
 PackedDataContainerRef::PackedDataContainerRef() {
+	offset = 0;
 }
diff --git a/core/script_debugger_local.cpp b/core/script_debugger_local.cpp
index e9bb07f594..3003ea1283 100644
--- a/core/script_debugger_local.cpp
+++ b/core/script_debugger_local.cpp
@@ -384,6 +384,10 @@ void ScriptDebuggerLocal::send_error(const String &p_func, const String &p_file,
 
 ScriptDebuggerLocal::ScriptDebuggerLocal() {
 	profiling = false;
+	frame_time = 0.0f;
+	idle_time = 0.0f;
+	physics_time = 0.0f;
+	physics_frame_time = 0.0f;
 	idle_accum = OS::get_singleton()->get_ticks_usec();
 	options["variable_prefix"] = "";
 }