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Arbitrary Datum

From MLabs Common Plutus Vulnerabilities

3. Arbitrary datum​

Identifier: arbitrary-datum

Property statement: Correctness of the datum is checked for all legit UTxOs locked by the protocol.

Test: A transaction can successfully lock in the protocol a legit UTxO with an arbitrary datum, making consumption in a second transaction fail.

Impact:

  • Unspendable outputs
  • Protocol halting

**Further explanation: It could be tempting to omit checks for the datum of an output being locked in a script when this datum is not going to be explicitly used in the validation of the future spending transaction. However, this is a dangerous practice as the type of the datum carried by a UTxO locked in a validator still needs to match the datum type expected by the validator. Otherwise, a transaction trying to consume the locked UTxO will fail, even if nothing was going to be checked about the information contained in the datum.