A low-privileged remote attacker can exploit the ubr-editfile method in wwwubr.cgi, an undocumented and unused API endpoint to write arbitrary files on the system.
Exploitability
AV:NAC:LPR:LUI:NScope
S:UImpact
C:NI:HA:H8.1/CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:HOther