{"id":"CVE-2026-45103","published":"2026-08-04T22:17:14.847","lastModified":"2026-08-05T19:17:30.650","description":"OpenSIPS is a Session Initiation Protocol (SIP) server implementation. In versions prior to 3.6.6 and 4.0.0-rc1, the TCP message framing layer parses the Content-Length header using unsigned int arithmetic with no overflow check. When an attacker sends a Content-Length value that overflows unsigned int (e.g., 4294967296), the framing layer computes a wrapped-around value (e.g., 0) and splits the TCP stream at the wrong boundary, causing the body of the first SIP message to be processed as a separate message and enabling SIP message smuggling. Because Content-Length is parsed in the transport layer before authentication, an unauthenticated, network-based attacker can smuggle arbitrary SIP messages over any TCP-based transport (proto_tcp, proto_tls, proto_ws, proto_wss) on any instance with TCP enabled, with no routing-script preconditions. This allows smuggled messages to bypass front-end SBC/proxy security policies, inherit the connection's authentication context, and evade rate limiting. This issue has been fixed in versions 3.6.6 and 4.0.0-rc1.","cvssScore":7.5,"cvssSeverity":"HIGH","cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N","cwes":["CWE-190"],"vendors":[],"products":[],"references":[{"url":"https://github.com/OpenSIPS/opensips/commit/4d23613b","tags":[]},{"url":"https://github.com/OpenSIPS/opensips/commit/5f103eff","tags":[]},{"url":"https://github.com/OpenSIPS/opensips/security/advisories/GHSA-jv35-555v-54jh","tags":[]}],"exploitRefs":[{"url":"https://github.com/OpenSIPS/opensips/commit/4d23613b","tags":[]},{"url":"https://github.com/OpenSIPS/opensips/commit/5f103eff","tags":[]},{"url":"https://github.com/OpenSIPS/opensips/security/advisories/GHSA-jv35-555v-54jh","tags":[]}],"hasPoc":true,"ai":{"summary":"The flaw allows an attacker to smuggle arbitrary SIP messages by exploiting unsigned int overflow in Content-Length parsing, bypassing security policies and rate limiting.","exploitability":"Exploitation is relatively easy for unauthenticated attackers with network access, requiring only sending a specific oversized Content-Length header.","blast_radius":"If exploited, this can significantly impact real-world systems by enabling unauthorized message smuggling across multiple transports, potentially leading to widespread security breaches.","remediation":"Update OpenSIPS to version 3.6.6 or later to mitigate the vulnerability.","tags":["sip","smuggling","auth-bypass","tcp"],"model":"qwen2.5:7b-instruct","analyzedAt":"2026-08-11T06:55:07.757Z"}}