Improper Input Validation
OpenSIPS is a Session Initiation Protocol (SIP) server implementation. In versions prior to 3.1.7, and 3.2.x prior to 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`.
CWE-20 - Improper Input Validation
The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.