Design/Logic Flaw

OpenSIPS is a Session Initiation Protocol (SIP) server implementation. Prior to versions 3.1.7 and 3.2.4, when the function append_hf handles a SIP message with a malformed To header, a call to the function abort() is performed, resulting in a crash. This is due to the following check in data_lump.c:399 in the function anchor_lump. An attacker abusing this vulnerability will crash OpenSIPS leading to Denial of Service. It affects configurations containing functions that make use of the affected code, such as the function append_hf. This issue has been fixed in versions 3.1.7 and 3.2.4.