CVE-2023-27601

OpenSIPS is a Session Initiation Protocol (SIP) server implementation. Prior to versions 3.1.7 and 3.2.4, OpenSIPS crashes when a malformed SDP body is received and is processed by the delete_sdp_line function in the sipmsgops module. This issue can be reproduced by calling the function with an SDP body that does not terminate by a line feed (i.e. \n).

The vulnerability was found while performing black-box fuzzing against an OpenSIPS server running a configuration that made use of the functions codec_delete_except_re and codec_delete_re. The same issue was also discovered while performing coverage guided fuzzing on the function codec_delete_except_re. The crash happens because the function delete_sdp_line expects that an SDP line is terminated by a line feed (\n):

By abusing this vulnerability, an attacker is able to crash the server. It affects configurations containing functions that rely on the affected code, such as the function codec_delete_except_re. Due to the sanity check that is performed in the del_lump function, exploitation of this issue will generate an abort in the lumps processing function, resulting in a Denial of Service. This issue has been fixed in versions 3.1.7 and 3.2.4.