The 19-year-old made an impression on Gladbach chiefs during his spell at the club earlier this season, when making four senior appearances - three of those in the Bundesliga.
Gladbach hoped to bring in the England Under-20s international on a permanent £10m deal this month, but were also happy to settle for a similar loan arrangement until the summer before opening discussions.
Oxford, also sent out to Reading last term, is unlikely to be leaving the London Stadium for a third time, however, as Sky Sports News suggests that Moyes intends to stand in the way of his exit.
Moyes believes that the versatile defensive midfielder can play a part between now and the end of the campaign, having been used three times over the past fortnight.
The transfer window in Germany closes at 5pm UK time.