(Pwn2Own) TP-Link Omada ER605 PPTP VPN username Command Injection Remote Code Execution Vulnerability

This vulnerability allows network-adjacent attackers to execute arbitrary code on affected installations of TP-Link Omada ER605 routers. Authentication is not required to exploit this vulnerability. However, devices are only vulnerable if configured to use a PPTP VPN with LDAP authentication. The specific flaw exists within the handling of the username parameter provided to the /usr/bin/pppd endpoint. The issue results from the lack of proper validation of a user-supplied string before using it to execute a system call. An attacker can leverage this vulnerability to execute code in the context of root.