Data planes are responsible for forwarding packets in a network. The P4 language is used for programming programmable data planes. Such data planes give more flexibility to programmers by allowing them to define how the packets should be processed. However, these data planes might also be more vulnerable to malicious attacks than traditional (non-programmable) data planes. That is because software is usually more prone to errors as compared to the hardware. Different research has already analyzed various aspects of the security of the P4 language. However, the security vulnerabilities of P4 programs have not been researched in depth. The main contribution of this paper is providing examples of attacks on P4 programs by using manipulated packet data. In this research, it was attempted to corrupt three P4 programs by manipulating packet data. Two of the three attempts were successful. The paper concludes that some P4 programs can be corrupted by malicious packets.