diff --git a/src/consensus/tx_check.cpp b/src/consensus/tx_check.cpp
index f15b60d49..e5ac1aa5d 100644
--- a/src/consensus/tx_check.cpp
+++ b/src/consensus/tx_check.cpp
@@ -1,102 +1,108 @@
 // Copyright (c) 2017-2018 The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #include <coins.h>
 #include <consensus/consensus.h>
 #include <consensus/validation.h>
 #include <primitives/transaction.h>
 #include <version.h>
 
 #include <unordered_set>
 
 static bool CheckTransactionCommon(const CTransaction &tx,
                                    CValidationState &state) {
     // Basic checks that don't depend on any context
     if (tx.vin.empty()) {
         return state.Invalid(ValidationInvalidReason::CONSENSUS, false,
                              REJECT_INVALID, "bad-txns-vin-empty");
     }
 
     if (tx.vout.empty()) {
         return state.Invalid(ValidationInvalidReason::CONSENSUS, false,
                              REJECT_INVALID, "bad-txns-vout-empty");
     }
 
     // Size limit
     if (::GetSerializeSize(tx, PROTOCOL_VERSION) > MAX_TX_SIZE) {
         return state.Invalid(ValidationInvalidReason::CONSENSUS, false,
                              REJECT_INVALID, "bad-txns-oversize");
     }
 
     // Check for negative or overflow output values
     Amount nValueOut = Amount::zero();
     for (const auto &txout : tx.vout) {
         if (txout.nValue < Amount::zero()) {
             return state.Invalid(ValidationInvalidReason::CONSENSUS, false,
                                  REJECT_INVALID, "bad-txns-vout-negative");
         }
 
         if (txout.nValue > MAX_MONEY) {
             return state.Invalid(ValidationInvalidReason::CONSENSUS, false,
                                  REJECT_INVALID, "bad-txns-vout-toolarge");
         }
 
         nValueOut += txout.nValue;
         if (!MoneyRange(nValueOut)) {
             return state.Invalid(ValidationInvalidReason::CONSENSUS, false,
                                  REJECT_INVALID,
                                  "bad-txns-txouttotal-toolarge");
         }
     }
 
     return true;
 }
 
 bool CheckCoinbase(const CTransaction &tx, CValidationState &state) {
     if (!tx.IsCoinBase()) {
         return state.Invalid(ValidationInvalidReason::CONSENSUS, false,
                              REJECT_INVALID, "bad-cb-missing",
                              "first tx is not coinbase");
     }
 
     if (!CheckTransactionCommon(tx, state)) {
         // CheckTransactionCommon fill in the state.
         return false;
     }
 
     if (tx.vin[0].scriptSig.size() < 2 ||
         tx.vin[0].scriptSig.size() > MAX_COINBASE_SCRIPTSIG_SIZE) {
         return state.Invalid(ValidationInvalidReason::CONSENSUS, false,
                              REJECT_INVALID, "bad-cb-length");
     }
 
     return true;
 }
 
 bool CheckRegularTransaction(const CTransaction &tx, CValidationState &state) {
     if (tx.IsCoinBase()) {
         return state.Invalid(ValidationInvalidReason::CONSENSUS, false,
                              REJECT_INVALID, "bad-tx-coinbase");
     }
 
     if (!CheckTransactionCommon(tx, state)) {
         // CheckTransactionCommon fill in the state.
         return false;
     }
 
     std::unordered_set<COutPoint, SaltedOutpointHasher> vInOutPoints;
     for (const auto &txin : tx.vin) {
         if (txin.prevout.IsNull()) {
             return state.Invalid(ValidationInvalidReason::CONSENSUS, false,
                                  REJECT_INVALID, "bad-txns-prevout-null");
         }
 
+        // Check for duplicate inputs (see CVE-2018-17144)
+        // While Consensus::CheckTxInputs does check if all inputs of a tx are
+        // available, and UpdateCoins marks all inputs of a tx as spent, it does
+        // not check if the tx has duplicate inputs. Failure to run this check
+        // will result in either a crash or an inflation bug, depending on the
+        // implementation of the underlying coins database.
         if (!vInOutPoints.insert(txin.prevout).second) {
             return state.Invalid(ValidationInvalidReason::CONSENSUS, false,
                                  REJECT_INVALID, "bad-txns-inputs-duplicate");
         }
     }
 
     return true;
 }