CVE-2021-31802 — Out-of-bounds Write in Netgear R7000 Firmware

NETGEAR R7000 1.0.11.116 devices have a heap-based Buffer Overflow that is exploitable from the local network without authentication. The vulnerability exists within the handling of an HTTP request. An attacker can leverage this to execute code as root. The problem is that a user-provided length value is trusted during a backup.cgi file upload. The attacker must add a \n before the Content-Length header.