CVE-2026-45103Public exploitNetwork attack vector

SIP message smuggling via Content-Length integer overflow

Published Aug 4, 2026 · Updated Aug 4, 2026

SIP message smuggling in OpenSIPS 3.4.0 through 3.6.5 and 4.0.0-beta allows remote attackers to inject SIP messages over TCP. The tcp_parse_headers function in net/proto_tcp/tcp_common.h multiplies and adds Content-Length digits into a 32-bit unsigned integer without checking overflow, so a wrapped length splits the stream early and reparses the remaining body. Any TCP-based SIP transport reaches this parser before authentication; smuggled messages can bypass upstream proxy policy, inherit connection trust, and evade per-request rate limits.

CVSS severity7.5
High
EPSS probability0.33%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

SIP message smuggling in OpenSIPS 3.4.0 through 3.6.5 and 4.0.0-beta allows remote attackers to inject SIP messages over TCP. The tcp_parse_headers function in net/proto_tcp/tcp_common.h multiplies and adds Content-Length digits into a 32-bit unsigned integer without checking overflow, so a wrapped length splits the stream early and reparses the remaining body. Any TCP-based SIP transport reaches this parser before authentication; smuggled messages can bypass upstream proxy policy, inherit connection trust, and evade per-request rate limits.

The record

CVE
CVE-2026-45103
Published
Aug 4, 2026
Updated
Aug 4, 2026
Vendor
OpenSIPS
Product
OpenSIPS
Classifications
CWE-190, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 4, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>= 3.4.0, < 3.6.6
  2. Affected versionversion=>= 4.0.0-beta, < 4.0.0-rc1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

OpenSIPS · OpenSIPSversion=>= 3.4.0, < 3.6.6; version=>= 4.0.0-beta, < 4.0.0-rc1

Published CVSS scores

7.5GitHub CNACVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-190Integer Overflow or Wraparound
T1190Exploit Public-Facing Application

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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