Guitarist Gannon, who toured with the How Soon Is Now? hitmakers in 1986, was the target for several catty remarks in the tome, including Morrissey's belief that hiring him was "a fascinating bungle".
In the book, titled Autobiography, Morrissey also takes a personal swipe at Gannon, writing, "Nothing useful vibrates in Craig's upper storey".
Now the guitarist has hit back, posting a message on his Facebook.com that reads, "Blatant bitter lies, all will become clear very soon..."
The message was posted on Thursday (31Oct13) but had been removed by Friday morning (01Nov13).
It came less than a day after another popular music industry figure, former The Smiths studio engineer Stephen Street, also blasted Morrissey for using the book to make cruel comments about his former colleagues.
Street, who worked on three of The Smiths' four studio albums and co-wrote tracks for Morrissey's solo debut Viva Hate in 1988, insists he is "amazed" by some of the "b**chy" comments in the book and believes it has finally killed off any remote chance of the band reuniting.
Hotpress.com quotes Street as saying, "People have often asked me, 'Do you think The Smiths will ever reform?'. I always thought it unlikely. Having read three-quarters of Morrissey's book I would now say there's not a hope in hell.
"Honestly, I am amazed at some of the character assassinations and jibes at certain people's appearances in the book. People might say, 'Well, you got off lightly', and I agree I did but I don't enjoy seeing other people who contributed to the success of the band and his solo career being put down in such a b**chy matter. What does it achieve?"