Comment on: “Three-party quantum secure direct communication based on GHZ states” [Phys. Lett. A 354 (2006) 67]

The GHZ-state-based quantum secure direct communication (QSDC) protocol [X.-R. Jin, et al., Phys. Lett. A 354 (2006) 67] and its improved version [Z. Man, Y. Xia, Chin. Phys. Lett. 24 (2007) 15] are analyzed from the aspect of security. It shows that much information of the transmitted secret message will be leaked out in both protocols.