---
cve: "CVE-2026-45103"
severity: "HIGH"
cvss: 7.5
epss: "33%"
vendor: "OpenSIPS"
kev: false
exploited: false
published: "2026-08-04 22:17:14"
tags: [cve, security, high]
source: tsecurity.de CVE-Dossier
exported: "2026-09-12T03:23:05+02:00"
---

# CVE-2026-45103

> 7.5 HIGH · 🧪 PoC

## Beschreibung

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.

## CVSS-Vektor

```
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Gering | bad |
| PR Privilegien | Keine | bad |
| UI Interaktion | Keine | bad |
| S Scope | Unverändert | good |
| C Vertraulichkeit | Keine | good |
| I Integrität | Hoch | bad |
| A Verfügbarkeit | Keine | good |

## Patch verfügbar (OSV)

- 26c0c4e3364806e77c2915b1c3e03bf9bd90dccd (Commit)
- b3621031661ed10d6af511d7c41f512075357a00 (Commit)

## Referenzen

- <https://github.com/OpenSIPS/opensips/security/advisories/GHSA-jv35-555v-54jh>
- <https://github.com/OpenSIPS/opensips/commit/4d23613b>
- <https://github.com/OpenSIPS/opensips/commit/5f103eff>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-45103) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_