The controversies concerning the surviving texts of the Satires have been extensive and heated. Many manuscripts survive, but only P (the Codex Pithoeanus Montepessulanus), a 9th-century manuscript based on an edition prepared in the 4th century by a pupil of Servius Honoratus, the grammarian, is reasonably reliable. At the same time as the Servian text was produced, however, other and lesser scholars also created their editions of Juvenal: it is these on which most medieval manuscripts of Juvenal are based. It did not help matters that P disappeared sometime during the Renaissance and was only rediscovered around 1840. It is not, however, uncommon for the generally inferior manuscripts to supply a better reading in cases when P is imperfect. In addition, modern scholarly debate has also raged around the authenticity of the text which has survived, as various editors have argued that considerable portions are not, in fact, authentically Juvenalian and represent interpolations from early editors of the text. Jachmann (1943) argued that up to one-third of what survives is non-authentic: Ulrick Knoche (1950) deleted about hundred lines, Clausen about forty, Courtney (1975) a similar number. Willis (1997) italicizes 297 lines as being potentially suspect. On the other hand, Vahlen, Housman, Duff, Griffith, Ferguson and Green believe the surviving text to be largely authentic: indeed Green regards the main problem as being not interpolations but lacunae.
In recent times debate has focused on the authenticity of the "O Passage" of Satire VI, 36 lines (34 of which are continuous) discovered by E.O. Winstedt in an 11th-century manuscript in Oxford's Bodleian Library. These lines occur in no other manuscript of Juvenal, and when discovered were considerably corrupted. Ever since Housman translated and emended the "O Passage" there has been considerable controversy over whether the fragment is in fact a forgery: the field is currently split between those (Green, Ferguson, Courtney) who believe it isn't, and those (Willis, Anderson), who believe it is.