An object-forwarding device can block a malicious Content Object from being inserted into an Interest's reverse path over a named data network. During operation, the device can receive a Content Object via a first interface, and can perform a lookup operation in a Pending Interest Table (PIT) to identify a PIT entry for an Interest associated with the Content Object. The device then determines, from the PIT entry, an egress interface used to forward the Interest. If the device determines that the egress interface of the PIT entry matches the first interface for the Content Object, the device forwards the Content Object via a return interface specified in the PIT entry. On the other hand, if the egress interface of the PIT entry does not match the first interface for the Content Object, the device can block the Content Object.