Missing ingredient from Peach Salsa can I recan
The key here is really how long it sits out at room temperature before you realize. The vinegar is acidic, so presumably it's part of bringing the pH to a safe one for boiling water canning. Without it, the salsa won't be safe to can like this.

If you realize right away and recan immediately, it's basically just cooking it extra. It may not be as good with the extra cooking, but it'll be safe. Similarly, if you immediately refrigerate then reheat, it spends a bit longer in the danger zone, but it should be easily within a safe margin.

On the other hand, if it sits out for hours, all bets are off. You made something not safe to store at room temperature, then stored it at room temperature, so you really can't know it's still safe.