SIP Express Router Missing To in ACK DoS

Summary
The remote host is a SIP Express Router (SER). The SER product has been found to contain a vulnerability where ACKs requests without a To header, when SER has been enabled to use the SL module, can be used to crash the product.
Solution
Upgrade to version 0.8.10. For additional details see: http://www.cert.org/advisories/CA-2003-06.html