SIP Message Smuggling Vulnerability in OpenSIPS Server
CVE-2026-45103

7.5HIGH

Key Information:

Vendor

Opensips

Status
Opensips
Vendor
CVE Published:
4 August 2026

What is CVE-2026-45103?

An issue in OpenSIPS, a Session Initiation Protocol (SIP) server, allows attackers to exploit the TCP message framing layer. In versions prior to 3.6.6 and 4.0.0-rc1, the parsing of the Content-Length header does not properly check for integer overflow. This oversight enables malicious actors to manipulate the Content-Length field, causing a wrapped-around value that leads to the misprocessing of SIP messages. As a result, an unauthenticated attacker can smuggle arbitrary SIP messages through any TCP-based transport, bypassing security policies and rate limiting measures. This vulnerability has been corrected in subsequent updates, emphasizing the importance of maintaining up-to-date software.

Affected Version(s)

opensips >= 3.4.0, < 3.6.6 < 3.4.0, 3.6.6

opensips >= 4.0.0-beta, < 4.0.0-rc1 < 4.0.0-beta, 4.0.0-rc1

References

https://github.com/OpenSIPS/opensips/security/advisories/...
x_refsource_CONFIRM
https://github.com/OpenSIPS/opensips/commit/4d23613b
x_refsource_MISC
https://github.com/OpenSIPS/opensips/commit/5f103eff
x_refsource_MISC

CVSS V3.1

Score:
7.5
Severity:
HIGH
Confidentiality:
None
Integrity:
High
Availability:
None
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
None
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

.