This document normatively updates RFC 3261, the Session Initiation
(SIP), to address a security vulnerability identified in SIP proxy
This vulnerability enables an attack against SIP networks where a small
number of legitimate, even authorized, SIP requests can stimulate massive
amounts of proxy-to-proxy traffic.
This document strengthens loop-detection requirements on SIP proxies
when they fork requests (that is, forward a request to more than one
It also corrects and clarifies the description of the loop-detection
algorithm such proxies are required to implement.
Working Group Summary
The document was produced by the SIP working group. There is consensus in
the WG to publish this document.
The document has been produced as a result of an issue identified during
SIPit interoperability testing.