The firmware update mechanism does not include cryptographic signature validation. This allows anyone with access to the firmware update capability to upload arbitrary files which can then lead to arbitrary code execution.
Exploitability
AV:NAC:LAT:NPR:NUI:NVulnerable System
VC:HVI:HVA:HSubsequent System
SC:LSI:LSA:L9.3/CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:L/SI:L/SA:LOther