CVE-2026-39863: Kamailio

High severity, CVSS 7.5. EPSS: 0.5% chance of exploitation in the next 30 days.

Kamailio is an open source implementation of a SIP Signaling Server. Prior to 6.1.1, 6.0.6, and 5.8.8, an out-of-bounds access in the core of Kamailio (formerly OpenSER and SER) allows remote attackers to cause a denial of service (process crash) via a specially crafted data packet sent over TCP. The issue impacts Kamailio instances having TCP or TLS listeners. This vulnerability is fixed in 5.1.1, 6.0.6, and 5.8.8.

Affected products

• Kamailio Kamailio: before 5.8.8 (fixed in 5.8.8); from 6.0.0, before 6.0.6 (fixed in 6.0.6); version 6.1.0 only

Published 2026-04-08. Last modified 2026-07-24.