diff --git a/td/mtproto/SessionConnection.cpp b/td/mtproto/SessionConnection.cpp
index 4f319851a..d95ec30ef 100644
--- a/td/mtproto/SessionConnection.cpp
+++ b/td/mtproto/SessionConnection.cpp
@@ -479,6 +479,7 @@ Status SessionConnection::on_slice_packet(const MsgInfo &info, Slice packet) {
   }
   TlParser parser(packet);
   tl_object_ptr<mtproto_api::Object> object = mtproto_api::Object::fetch(parser);
+  parser.fetch_end();
   if (parser.get_error()) {
     // msg_container is not real tl object
     if (packet.size() >= 4 && as<int32>(packet.begin()) == mtproto_api::msg_container::ID) {
diff --git a/td/telegram/ConfigManager.cpp b/td/telegram/ConfigManager.cpp
index 95f5f3dde..095aec6d9 100644
--- a/td/telegram/ConfigManager.cpp
+++ b/td/telegram/ConfigManager.cpp
@@ -102,16 +102,17 @@ Result<SimpleConfig> decode_config(Slice input) {
 
   TlParser len_parser{data_cbc};
   int len = len_parser.fetch_int();
-  if (len < 0 || len > 204) {
+  if (len < 8 || len > 208) {
     return Status::Error(PSLICE() << "Invalid " << tag("data length", len) << " after aes_cbc_decrypt");
   }
   int constructor_id = len_parser.fetch_int();
   if (constructor_id != telegram_api::help_configSimple::ID) {
     return Status::Error(PSLICE() << "Wrong " << tag("constructor", format::as_hex(constructor_id)));
   }
-  BufferSlice raw_config(data_cbc.substr(8, len));
+  BufferSlice raw_config(data_cbc.substr(8, len - 8));
   TlBufferParser parser{&raw_config};
   auto config = telegram_api::help_configSimple::fetch(parser);
+  parser.fetch_end();
   TRY_STATUS(parser.get_status());
   return std::move(config);
 }
diff --git a/td/telegram/SecretChatActor.cpp b/td/telegram/SecretChatActor.cpp
index 27c5bafe0..1e6b7e3e1 100644
--- a/td/telegram/SecretChatActor.cpp
+++ b/td/telegram/SecretChatActor.cpp
@@ -895,6 +895,7 @@ Status SecretChatActor::do_inbound_message_encrypted(unique_ptr<logevent::Inboun
   Status status;
   if (id == secret_api::decryptedMessageLayer::ID) {
     auto message_with_layer = secret_api::decryptedMessageLayer::fetch(parser);
+    parser.fetch_end();
     if (!parser.get_error()) {
       auto layer = message_with_layer->layer_;
       if (layer < DEFAULT_LAYER && false /*TODO: fix android app bug? */) {
@@ -930,6 +931,7 @@ Status SecretChatActor::do_inbound_message_encrypted(unique_ptr<logevent::Inboun
   if (config_state_.his_layer == 8) {
     TlBufferParser new_parser(&data_buffer);
     auto message_without_layer = secret_api::DecryptedMessage::fetch(new_parser);
+    parser.fetch_end();
     if (!new_parser.get_error()) {
       message->decrypted_message_layer = secret_api::make_object<secret_api::decryptedMessageLayer>(
           BufferSlice(), config_state_.his_layer, -1, -1, std::move(message_without_layer));
diff --git a/td/telegram/Td.cpp b/td/telegram/Td.cpp
index 3d1f74ffe..e9422bf6c 100644
--- a/td/telegram/Td.cpp
+++ b/td/telegram/Td.cpp
@@ -3580,6 +3580,7 @@ void Td::on_result(NetQueryPtr query) {
     auto ok = query->move_as_ok();
     TlBufferParser parser(&ok);
     auto ptr = telegram_api::Updates::fetch(parser);
+    parser.fetch_end();
     if (parser.get_error()) {
       LOG(ERROR) << "Failed to fetch update: " << parser.get_error() << format::as_hex_dump<4>(ok.as_slice());
       updates_manager_->schedule_get_difference("failed to fetch update");