#fixed code
                                @Override
    public ValidateResult validate(AbstractCoinTransaction tx) {
        UtxoData data = (UtxoData) tx.getCoinData();
        for (int i = 0; i < data.getInputs().size(); i++) {
            UtxoInput input = data.getInputs().get(i);
            UtxoOutput output = input.getFrom();

            if (output == null && tx.getStatus() == TxStatusEnum.CACHED) {
                return ValidateResult.getFailedResult(ErrorCode.ORPHAN_TX);
            } else if (output == null) {
                return ValidateResult.getFailedResult(ErrorCode.UTXO_NOT_FOUND);
            }

            if (tx.getStatus() == TxStatusEnum.CACHED) {
                if (!output.isUsable()) {
                    return ValidateResult.getFailedResult(ErrorCode.UTXO_STATUS_CHANGE);
                }
            } else if (tx.getStatus() == TxStatusEnum.AGREED) {
                if (!output.isSpend()) {
                    return ValidateResult.getFailedResult(ErrorCode.UTXO_STATUS_CHANGE);
                }
            }

            byte[] owner = output.getOwner();
            P2PKHScriptSig p2PKHScriptSig = null;
            try {
                p2PKHScriptSig = P2PKHScriptSig.createFromBytes(tx.getScriptSig());
            } catch (NulsException e) {
                return ValidateResult.getFailedResult(ErrorCode.DATA_ERROR);
            }
            byte[] user = p2PKHScriptSig.getSignerHash160();
            if (!Arrays.equals(owner, user)) {
                return ValidateResult.getFailedResult(ErrorCode.INVALID_OUTPUT);
            }

            return ValidateResult.getSuccessResult();
        }
        return ValidateResult.getSuccessResult();
    }
#vulnerable code 
                                @Override
    public ValidateResult validate(AbstractCoinTransaction tx) {
        UtxoData data = (UtxoData) tx.getCoinData();
        for (int i = 0; i < data.getInputs().size(); i++) {
            UtxoInput input = data.getInputs().get(i);
            UtxoOutput output = input.getFrom();

            if (output == null && tx.getStatus() == TxStatusEnum.CACHED) {
                return ValidateResult.getFailedResult(ErrorCode.ORPHAN_TX);
            }

            if (tx.getStatus() == TxStatusEnum.CACHED) {
                if (!output.isUsable()) {
                    return ValidateResult.getFailedResult(ErrorCode.UTXO_STATUS_CHANGE);
                }
            } else if (tx.getStatus() == TxStatusEnum.AGREED) {
                if (!output.isSpend()) {
                    return ValidateResult.getFailedResult(ErrorCode.UTXO_STATUS_CHANGE);
                }
            }

            byte[] owner = output.getOwner();
            P2PKHScriptSig p2PKHScriptSig = null;
            try {
                p2PKHScriptSig = P2PKHScriptSig.createFromBytes(tx.getScriptSig());
            } catch (NulsException e) {
                return ValidateResult.getFailedResult(ErrorCode.DATA_ERROR);
            }
            byte[] user = p2PKHScriptSig.getSignerHash160();
            if (!Arrays.equals(owner, user)) {
                return ValidateResult.getFailedResult(ErrorCode.INVALID_OUTPUT);
            }

            return ValidateResult.getSuccessResult();
        }
        return ValidateResult.getSuccessResult();
    } 
                            #location 17 
                            #vulnerability type NULL_DEREFERENCE