If you happen to have one, a 3D printer pen* can act like a plastic welder in this case. I would recommend against doing this for PVC, but ABS is what those pens often already use.
I'd first drill a tiny hole, as I suggested in a comment on Ecnerwal good answer. It doesn't have to be large, just 1/16" (~2mm) at each end of the crack to relieve stress.
Then starting from one of these holes, shove in your hot 3D pen and start adding new ABS. Yes, the idea is to melt the pipe a bit and mix in the new ABS. This will be more than just a "filler" patch, which could leak. This is where you are melting the existing plastic and shoving in more ABS to fill the crack while making the new plastic part of the pipe itself. Don't worry about making it look clean, leave plenty of plastic bulging out of the crack, as that's how you are assured it's going to work the best. It's not a guarantee, but it's far better than not using enough and having a leak.
Using this method may take a while and probably include some nasty odors, so make sure you have time and airflow working for you. If you don't take your time to make this work, you are going to make the problem worse, not better.
This sounds like a permanent fix, but it's not. Some people might be tempted to use this as a permanent fix, but I don't recommend that. There's still plenty of room for error here. There are professional plastic welders that could be used for a permanent fix, but a 3D pen isn't that.
If the crack is a hairline, you could try using a plastic cement that slightly dissolves the plastic, but seeing as this is plumbing grade ABS, that might not actually soften the plastic. Also, you'll have to squeeze the edges of the pipe together to get them to bond, so you're creating extra stress on the pipe. It could work for a short time, maybe the weeks you need, but it might not.
When using plastic cement, make sure it goes all the way into the crack, or you aren't doing any sort of repair. Really thin, sometimes called "water thin", cements will do this for you, as long as you use enough. The thicker ones will need to be forced into the the crack as it's applied. Just shove the nozzle into the face of the crack and squeeze the cement so it bulges out the sides of the crack as you move along the crack. Again, you aren't trying to make this look pretty, you're trying to fix a pipe. Using "too much" is still better. Well, unless it's literally getting everywhere and you're wasting more than is in the crack.
If you or your kids make plastic models, the red tube of Testors cement* would be something to try. Unlike the blue stuff, this will slightly melt the plastic, and, because it's thick, will help fill the crack. Again, this is a temporary fix. And again, I'd start with drilling those strain relief holes.
* I'm not suggesting a retailer, it just happens to be an easy site to show the product(s) I'm talking about.