Yes. You have the right to sue the person or persons who cause you bodily harm while drinking at an outdoor concert festival. However, you were likely intoxicated before the episode resulting in injuries to your person, a judge might deem comparative negligence applies to the case.
This means that while you could have sustained considerable bodily harm, the presiding judge would also hold you responsible for any injuries you may have inflicted on the defendant. In this scenario, the defendant would be required to compensate you for your injuries, and you would also be obligated to do the same for his/her injuries.
Furthermore, you may choose to sue the event organizers as they would be obligated to oversee security at the outdoor concert venue. In this scenario, the grounds of your personal injury lawsuit would be negligence in enforcing security on the part of the event organizers.