An issue in kamailio v.6.1.1 and before allows a remote attacker to cause a denial of service via the ims_registrar_pcscf module, specifically the pcscf_save_pending/save_pending path and security-agreement parsing in sec_agree.c:parse_sec_agree()
https://github.com/kamailio/kamailio/issues/4671
https://github.com/kamailio/kamailio/commit/722c06b3efc53ccb369ce812c685c7d069508187