Wow. Months, huh?
Of course, it'll depend a lot on how "clear" the stock is, and how it was initially prepared/how good your antimicrobial controls were… But if it's under a year or two, there's minimal 'freezer burn', and you're not financially in a position to toss it out of hand, just add some salt and overcook it a bit.
Judging from the lawsuit-fearing bastions of Internet cooking, realistically you're looking at 4-6 months, which is again likely 50% reduction from anything like an actual limit (which makes my year totally reasonable). And, you know, if there are no starvation concerns, it's like eating stale non-moldy bread… Probably not gonna kill you, but may impact your dish's flavor enough to make eating it much less pleasant than if you "started fresh".