According to JKR's own description of Veritaserum, use of the serum...
"...would have you spilling your innermost secrets". - Harry Potter and the Goblet of Fire
Although it may force you to accept a truth you've been denying yourself (that you were in love with someone, for example) it doesn't seem to grant you any insight into things that you don't already know. In that sense, it can only reveal the subjective truth, albeit one unvarnished by personal prejudices.
Note also, that a powerful wizard can hide things even from themselves so it's actually pretty useless as an interrogation tool unless the victim is caught unawares:
Q. Veritaserum plays a big part in finding out the truth from Mad-Eye Moody in book four. Why then is it not used for example in the
trials mentioned in the same book? It would be much easier in solving
problems like whether Sirius Black was guilty or not?
JKR : Veritaserum works best upon the unsuspecting, the vulnerable and those insufficiently skilled (in one way or another) to
protect themselves against it. Barty Crouch had been attacked before
the potion was given to him and was still very groggy, otherwise he
could have employed a range of measures against the Potion - he might
have sealed his own throat and faked a declaration of innocence,
transformed the Potion into something else before it touched his lips,
or employed Occlumency against its effects. In other words, just like
every other kind of magic within the books, Veritaserum is not
infallible. As some wizards can prevent themselves being affected, and
others cannot, it is an unfair and unreliable tool to use at a trial.
Sirius might have volunteered to take the potion had he been given the chance, but he was never offered it. Mr. Crouch senior, power mad
and increasingly unjust in the way he was treating suspects, threw him
into Azkaban on the (admittedly rather convincing) testimony of many
eyewitnesses. The sad fact is that even if Sirius had told the truth
under the influence of the Potion, Mr. Crouch could still have
insisted that he was using trickery to render himself immune to it.