{"id":"CVE-2026-45103","title":"OpenSIPS is a Session Initiation Protocol (SIP) server implementation","summary":"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…","severity":"high","cvss":7.5,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N","cwe":["CWE-190"],"published":"2026-08-04","updated":"2026-09-08","sourceUpdated":"2026-09-08T20:41:31.497","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-45103","references":[{"url":"https://github.com/OpenSIPS/opensips/commit/4d23613b","label":"security-advisories@github.com"},{"url":"https://github.com/OpenSIPS/opensips/commit/5f103eff","label":"security-advisories@github.com"},{"url":"https://github.com/OpenSIPS/opensips/security/advisories/GHSA-jv35-555v-54jh","label":"security-advisories@github.com"}],"tags":["nvd"],"epss":0.00328,"epssPercentile":0.2607,"ingestedAt":"2026-09-08T21:11:12.266Z","slug":"CVE-2026-45103","body":"## Overview\n\nOpenSIPS 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.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":41,"depthScoreParts":{"impact":41.3,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}