Improper frame handling in the Zyxel XGS2220-30 firmware version V4.80(ABXN.1), XMG1930-30 firmware version V4.80(ACAR.1), and XS1930-10 firmware version V4.80(ABQE.1) could allow an unauthenticated LAN-based attacker to cause denial-of-service (DoS) conditions by sending crafted frames to an affected switch.