4. Security Considerations

The specific protocol modifications described in this document are not known to create any security concerns that are not already present when IGMPv3 or MLDv2 is used with ASM-style multicast. The reader is referred to [SSM] for an analysis of SSM-specific security issues.

It is important that a router not accept non-source-specific reception requests for an SSM destination address. The rules of [IGMPv3] and [MLDv2] require a router, upon receiving such a membership report, to revert to earlier version compatibility mode for the group in question. If the router were to revert in this situation, it would prevent an IGMPv3-capable host from receiving SSM service for that destination address, thus creating a potential for an attacker to deny SSM service to other hosts on the same link.