This is what the illustrious theologian and scholar St. Jerome wrote in regards to the canonicity of Judith. All emphasis is mine.
Jerome, Prologue to Judith (2006)
[Translated by Kevin P. Edgecomb]
BEGINNING OF THE PROLOGUE TO JUDITH
Among the Hebrews the Book of Judith is found among the Hagiographa, the authority of which toward confirming those which have come into contention is judged less appropriate. Yet having been written in Chaldean words, it is counted among the histories. But because this book is found by the Nicene Council to have been counted among the number of the Sacred Scriptures, I have acquiesced to your request, indeed a demand, and works having been set aside from which I was forcibly curtailed, I have given to this (book) one short night’s work translating more sense from sense than word from word. I have removed the extremely faulty variety of the many books; only those which I was able to find in the Chaldean words with understanding intact did I express in Latin ones.
Receive the widow Judith, an example of chastity, and declare triumphal honor with perpetual praises for her. For this one, imitable not only for women, but also for men, has the Rewarder of her chastity given, Who has granted such strength, that she conquered the one unconquered by all men, she surpassed the insurpassable.
END OF THE PROLOGUE
FURTHER READING
Jerome’s Preface to the Book of Judith (c. A.D. 407)
The Biblical Canon of the 5th-6th Centuries
Gregory of Nazianzus’ Biblical Canon
The Synod of Laodicea’s Biblical Canon
John of Damascus’ Biblical Canon
Answering Islam Blog 