FreeBSD Security Advisory - There is no mechanism for preventing IPv6 routing headers from being used to route packets over the same link(s) many times. An attacker can "amplify" a denial of service attack against a link between two vulnerable hosts; that is, by sending a small volume of traffic the attacker can consume a much larger amount of bandwidth between the two vulnerable hosts. An attacker can use vulnerable hosts to "concentrate" a denial of service attack against a victim host or network; that is, a set of packets sent over a period of 30 seconds or more could be constructed such that they all arrive at the victim within a period of 1 second or less.
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