The short answer is yes, in the sense that you won't just get away with it.

The long answer is, as you're probably aware if you've spent any amount of time on this sub: it's a bit more complicated than that.

The first thing is that you havn't specified a time or place. For the purposes of this answer let's assume that the place is Northern France (because, for better or worse, that's the default place in medieval history) and we're in and around the year 1100.

(Huh, that's weird, that's the place and time period I know best! What a coinky-dink!)

The first thing which matters is your relationship with the lord you're raiding. You wouldn't just raid his land for kicks. You might be in a feud with him - for example if he insulted you or killed your nephew or something like that. You might be on opposite sides of a local dispute - you support opposing candidates for a vacant local bishopric. You might be an ambitious, expansionist person - you want to start a war and take over some or all of his lands.

All of these factors will effect how likely it is that you will experience retribution. The main reason that medieval lords fought with each other was to try to force the other party to the negotiating table, or to a superior court where both parties would accept the judgement handed down. But no matter what you did, you'll get a response from your enemy.

Two responses are likely to get your mutual lord involved. The first is if your enemy goes to the lord to complain about your behaviour. The second is if your enemy fights back in a tit-for-tat feud, in which case it probably won't be long before the lord steps in himself, in order to settle things down: after all, noone wants their influential supporters ripping each other apart.

If your lord gets involved, you're unlikely to be punished in the sense that a modern court would punish you for burning down your neighbour's house. The lord's reactions would depend a whole range of variables, the most important being your relationship with him and your enemy's relationship with him. Everyone's relationship with neighbouring lords would matter a lot too - if you were also close to your lord's rival, then if you didn't like how things were going, you could jump ship and swear fealty to his rival. So things can get very complicated, very quickly.

There were no laws or regulations which defined what you could and could not do as someone's vassal and what you could get punished for. So how the lord decided to get involved was important. If he decided to arbitrate the dispute, you would both but forward your cases and the lord would try to come up with an acceptable solution that would allow both sides to save face. If he sided with one side or the other, they would most likely gang up on the third party and force him, through violence and negotiations, to accept their demands. This is why your relationship with the lord matters so much. If you're a powerful, rich vassal, married to your lord's sister and almost as rich as him, he needs to keep you on side and is going to struggle to extract a compromise from you or to beat you down. So even if you're in the wrong, odds are he'll back you and let you away with things. If on the other hand, you're relatively weak, your lord might support you in an effort to bring down an uppity underling and potential rival.

TL;DR: There are millions of possible permutations on this situation, mainly because there was no system, laws or set of rules to solve these kinds of disputes. Arbitration and compromises, with every party weighing up their options for greater gain via violence, treachery etc., were the rule. This is what Stephen White has called "feudal politics" and most of this answer is drawn from his work, in particular his Feuding and Peace-making in Eleventh-Century France (Ashgate, 2005). For lots of well contexualised, real world examples of this sort of local politics and warfare see Richard Barton, Lordship in the County of Maine, c. 890-1160 (Woodbridge, 2004).