Please read the following thread: https://bitcointalk.org/index.php?topic=140078.0

Also additional information was privately sent to the dev team.

My proposed solutions is:

1. Create a Transaction hash cache to temporarily store the last used hash during the evaluation of a script.
2. Verify that the ECDSA signature and the ECDSA public key are well-formed before hashing the transaction.
3. Verify the length of pushed signatures of vin[i].scriptSig in CTransaction::AreInputsStandard() to see if they are long enough.
   (currently only stack.size() = (unsigned int)nArgsExpected) is tested, but not the actual arguments. )

The first 2 defense measures must be deployed together.