1 files changed, 8 insertions, 0 deletions
diff --git a/src/main.cpp b/src/main.cpp
index 2b102e5b9d..df8f7efa22 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -362,6 +362,14 @@ bool CTransaction::IsStandard() const
     if (!IsFinal())
         return false;
 
+    // Extremely large transactions with lots of inputs can cost the network
+    // almost as much to process as they cost the sender in fees, because
+    // computing signature hashes is O(ninputs*txsize). Limiting transactions
+    // to MAX_STANDARD_TX_SIZE mitigates CPU exhaustion attacks.
+    unsigned int sz = this->GetSerializeSize(SER_NETWORK, CTransaction::CURRENT_VERSION);
+    if (sz >= MAX_STANDARD_TX_SIZE)
+        return false;
+
     BOOST_FOREACH(const CTxIn& txin, vin)
     {
         // Biggest 'standard' txin is a 3-signature 3-of-3 CHECKMULTISIG