DHCP routing options can manipulate interface-based VPN traffic
DHCP can add routes to a client’s routing table via the classless static route option (121). VPN-based security solutions that rely on routes to redirect traffic can be forced to leak traffic over the physical interface. An attacker on the same local network can read, disrupt, or possibly modify network traffic that was expected to be protected by the VPN.
An issue was discovered in the Clario VPN client through 5.9.1.1662 for macOS. The VPN client insecurely configures the operating system such that traffic to the local network is sent in plaintext outside the VPN tunnel even if the local network is using a non-RFC1918 IP subnet. This allows an adversary to trick the victim into sending arbitrary IP traffic in plaintext outside the VPN tunnel. NOTE: the tunnelcrack.mathyvanhoef.com website uses this CVE ID to refer more generally to "LocalNet attack resulting in leakage of traffic in plaintext" rather than to only Clario.
The WireGuard client 0.5.3 on Windows insecurely configures the operating system and firewall such that traffic to a local network that uses non-RFC1918 IP addresses is blocked. This allows an adversary to trick the victim into blocking IP traffic to selected IP addresses and services even while the VPN is enabled. NOTE: the tunnelcrack.mathyvanhoef.com website uses this CVE ID to refer more generally to "LocalNet attack resulting in the blocking of traffic" rather than to only WireGuard.
WireGuard, such as WireGuard 0.5.3 on Windows, does not fully account for the possibility that an adversary might be able to set a victim's system time to a future value, e.g., because unauthenticated NTP is used. This can lead to an outcome in which one static private key becomes permanently useless.