The photo is authentic. It is in numerous reliable archives. The exact time given in one wikipedia is just overly precise. That is: wrong. No other Wikipedia page gives that time.
French Wikipedia: On November 11, 1918, around 5:30 a.m., just after the signing of the treaty, at the exit of the "Armistice wagon": in the foreground with a cane and a kepi, Marshal Foch, surrounded by the British admirals Hope (right) and Wemyss (left).
Looking at the picture more closely reveals things Evargalo noticed in a comment:
I don't believe artificial lights could help taking such a picture by night. It might enlighten the front scene (the characters and the wagon), but not the trees in the background. The clear sky in between the trees on top of the picture can only be explained by daylight or (very unlikely) later photo-editing.
Then there are the natural soft shadows from diffuse illumination indicating a certain early time of day. The absence of harsh contrasts points into that direction as well.
Earlier, when Foch signed the document, this photo was taken:
More importantly, other sources give another time:
The only known photo of the Copiègne armistice on 11 November 1918 at 7:30 a.m. shows the "winners": front from left: Naval officer George Hope, General Maxime Weygand, Naval officer Rosslyn Wemyss, Marshal Ferdinand Foch, Captain Marriott, Naval officer Jack Marriott. At the top of the stairs Commander Riedinger and the translator Laperche, in front General Desticker and Captain of the Mierry. (Source) (Alternative src, same time given, PDF)
And directly asking google gives this
06:52, Monday, 11. November 1918 (GMT)
sunrise in Compiègne, France
Whether it's a typo or not, for me that is still shortly after the signing, as soon as lighting allowed.
The exactness of the minute is of low certainty. Wartime, summer time, double-summer-time, even in November, all factor in. Local time for Germany, solar time at the place, British time; French time should be CET zone as well.
It is doubtful that the photographer really noted the exact time when he took the picture and I suspect that all those times given around the net are pseudo precise, as they all seem to extrapolate from 'reasons'.
Just one thing is sure: those people did not sign the papers, get immediately to a picture and then cable important instructions or celebrate before dawn. The photo was staged sometime after signing and when lighting was good.