** DISPUTED **  OpenSER 1.2.2 does not verify the Digest authentication header URI against the Request URI in SIP messages, which allows remote attackers to use sniffed Digest authentication credentials to call arbitrary telephone numbers or spoof caller ID (aka "toll fraud and authentication forward attack").  NOTE: Debian disputes this issue, stating that "having the two URIs mismatch is allowed by the standard and happens in some setups for valid reasons."