A stack-based buffer overflow vulnerability exists in the DHCP fingerprinting daemon (fingerd) of WatchGuard Fireware OS. This flaw allows an unauthenticated attacker with adjacent network access to execute arbitrary code or cause a denial of service by crashing the process via a specially crafted DHCP packet. The vulnerability is identified as CVE-2026-81433 and is classified as high severity. No affected versions or patch information are provided, and no known exploits are reported in the wild.