CVE-2026-91840: Networkmanager-vpnc: networkmanager-vpnc: local privilege escalation to root via newline injection in vpn username

A flaw was found in NetworkManager-vpnc. This vulnerability allows a local unprivileged user to escalate privileges to root. By injecting a newline character into the VPN username field, an attacker can manipulate the vpnc configuration to execute an arbitrary program with root privileges when the malicious VPN connection is activated.