{"description":"Trending threats, MITRE ATT\u0026CK coverage, and detection metadata — refreshed continuously.","feed_url":"https://feed.craftedsignal.io/tags/kamailio/","home_page_url":"https://feed.craftedsignal.io/","items":[{"_cs_actors":[],"_cs_cves":[{"cvss":7.5,"id":"CVE-2026-39863"}],"_cs_exploited":false,"_cs_products":[],"_cs_severities":["high"],"_cs_tags":["dos","cve-2026-39863","kamailio"],"_cs_type":"advisory","_cs_vendors":[],"content_html":"\u003cp\u003eKamailio, an open-source SIP signaling server, is susceptible to a denial-of-service vulnerability (CVE-2026-39863) affecting versions prior to 6.1.1, 6.0.6, and 5.8.8. The vulnerability stems from an out-of-bounds access issue in the core of Kamailio, which can be triggered by sending a specially crafted data packet over TCP.  This results in a process crash, effectively causing a denial-of-service condition.  The vulnerability specifically impacts Kamailio instances configured with TCP or TLS listeners, making them prime targets for exploitation.  Organizations using affected Kamailio versions are urged to upgrade to a patched release to mitigate the risk of service disruption.\u003c/p\u003e\n\u003ch2 id=\"attack-chain\"\u003eAttack Chain\u003c/h2\u003e\n\u003col\u003e\n\u003cli\u003eThe attacker identifies a Kamailio server running a vulnerable version (prior to 6.1.1, 6.0.6, or 5.8.8) with a TCP or TLS listener enabled.\u003c/li\u003e\n\u003cli\u003eThe attacker crafts a malicious SIP packet specifically designed to exploit the out-of-bounds access vulnerability (CVE-2026-39863).\u003c/li\u003e\n\u003cli\u003eThe attacker establishes a TCP connection to the Kamailio server on the designated SIP port (typically 5060 for TCP or 5061 for TLS).\u003c/li\u003e\n\u003cli\u003eThe attacker sends the crafted malicious SIP packet over the established TCP connection.\u003c/li\u003e\n\u003cli\u003eThe Kamailio server attempts to process the malicious packet.\u003c/li\u003e\n\u003cli\u003eDue to the out-of-bounds access vulnerability, the server attempts to read or write memory outside of the allocated buffer.\u003c/li\u003e\n\u003cli\u003eThis out-of-bounds memory access leads to a segmentation fault or other memory corruption error.\u003c/li\u003e\n\u003cli\u003eThe Kamailio process crashes, resulting in a denial-of-service condition, preventing legitimate SIP traffic from being processed.\u003c/li\u003e\n\u003c/ol\u003e\n\u003ch2 id=\"impact\"\u003eImpact\u003c/h2\u003e\n\u003cp\u003eSuccessful exploitation of CVE-2026-39863 results in a denial-of-service condition, rendering the Kamailio server unavailable for processing SIP requests. This can disrupt VoIP services, impact call routing, and prevent users from making or receiving calls. The severity of the impact depends on the criticality of the Kamailio server within the organization\u0026rsquo;s communication infrastructure. If a critical server fails, it could cause significant disruptions affecting hundreds or thousands of users.\u003c/p\u003e\n\u003ch2 id=\"recommendation\"\u003eRecommendation\u003c/h2\u003e\n\u003cul\u003e\n\u003cli\u003eUpgrade Kamailio installations to version 6.1.1, 6.0.6, or 5.8.8 or later to patch CVE-2026-39863.\u003c/li\u003e\n\u003cli\u003eImplement rate limiting on SIP traffic at the firewall level to mitigate the impact of potential denial-of-service attacks targeting Kamailio.\u003c/li\u003e\n\u003cli\u003eMonitor Kamailio server logs for abnormal process crashes or restarts, which could indicate exploitation attempts.\u003c/li\u003e\n\u003cli\u003eDeploy the Sigma rule below to detect suspicious network activity associated with potential exploitation attempts against Kamailio servers with TCP or TLS listeners.\u003c/li\u003e\n\u003c/ul\u003e\n","date_modified":"2026-04-08T20:16:26Z","date_published":"2026-04-08T20:16:26Z","id":"/briefs/2026-04-kamailio-dos/","summary":"A remote attacker can exploit an out-of-bounds access vulnerability (CVE-2026-39863) in Kamailio versions prior to 6.1.1, 6.0.6, and 5.8.8 by sending a specially crafted data packet over TCP, causing a denial-of-service condition.","title":"Kamailio Out-of-Bounds Access Denial of Service Vulnerability","url":"https://feed.craftedsignal.io/briefs/2026-04-kamailio-dos/"}],"language":"en","title":"CraftedSignal Threat Feed — Kamailio","version":"https://jsonfeed.org/version/1.1"}