PGP Desktop 10.0.x before 10.0.3 SP2 and 10.1.0 before 10.1.0 SP1 does not properly implement the "Decrypt/Verify File via Right-Click" functionality for multi-packet OpenPGP messages that represent multi-message input, which allows remote attackers to spoof signed data by concatenating an additional message to the end of a legitimately signed message, related to a "piggy-back" or "unsigned data injection" issue.