Session Initiation Protocol | Breaking Cybersecurity News | The Hacker News

Cybersecurity researchers on Tuesday disclosed details about a zero-click security vulnerability in the Linphone Session Initiation Protocol ( SIP ) stack that could be remotely exploited without any action from a victim to crash the SIP client and cause a denial-of-service (DoS) condition. Tracked as  CVE-2021-33056  (CVSS score: 7.5), the issue concerns a NULL pointer dereference vulnerability in the " belle-sip " component, a C-language library used to implement SIP transport, transaction, and dialog layers, with all versions prior to  4.5.20  affected by the flaw. The weakness was discovered and reported by industrial cybersecurity company Claroty. Linphone is an open-source and cross-platform SIP client with support for voice and video calls, end-to-end encrypted messaging, and audio conference calls, among others. SIP, on the other hand, is a signaling protocol used for initiating, maintaining, and terminating real-time multimedia communication sessions for voice, v