I just received word from an authoritative source on this vulnerability (actually the person that found it) and was informed that version 4.7.2B does not fix the DoS vulnerability. The only way to mitigate the risk is to block TCP port 80 on your concentrator (or upstream router/firewall), otherwise an attacker could send a stream of packets that takes out the concentrator and forces you to power cycle the box to get it back. Ouch.
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Thank you to Eldon Sprickerhoff for pointing this out.