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CVE-2026-45103— OpenSIPS: SIP Message Smuggling via TCP Content-Length Integer Overflow

Quick assessment

Affected
OpenSIPS opensips
Exploitation
Public or AI PoC available; prioritize validation
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

OpenSIPS是OpenSIPS组织开源的一个 GPL 许可的 SIP 服务器实现。 OpenSIPS 3.6.6之前版本和4.0.0-rc1之前版本存在数字错误漏洞，该漏洞源于TCP消息分帧层在解析Content-Length标头时使用无符号整数运算且未进行溢出检查，可能导致未经身份验证的网络攻击者通过发送溢出的Content-Length值实现SIP消息走私，绕过前端SBC/代理安全策略，继承连接的认证上下文，并规避速率限制。

CVSS 7.5 · High EPSS 0.58% · P46

Affected Version Matrix 2

VendorProduct Version RangeStatus
OpenSIPS opensips >= 3.4.0, < 3.6.6 affected
>= 4.0.0-beta, < 4.0.0-rc1 affected
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I. Basic Information for CVE-2026-45103

Vulnerability Information
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Vulnerability Title
OpenSIPS: SIP Message Smuggling via TCP Content-Length Integer Overflow
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
整数溢出或超界折返
Source: CVE Program / CVE List V5
Vulnerability Title
OpenSIPS 数字错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
OpenSIPS是OpenSIPS组织开源的一个 GPL 许可的 SIP 服务器实现。 OpenSIPS 3.6.6之前版本和4.0.0-rc1之前版本存在数字错误漏洞，该漏洞源于TCP消息分帧层在解析Content-Length标头时使用无符号整数运算且未进行溢出检查，可能导致未经身份验证的网络攻击者通过发送溢出的Content-Length值实现SIP消息走私，绕过前端SBC/代理安全策略，继承连接的认证上下文，并规避速率限制。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
OpenSIPS opensips >= 3.4.0, < 3.6.6 -

II. Public POCs for CVE-2026-45103

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Qwen3.6-35B-A3B · 8851 chars
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III. Intelligence Information for CVE-2026-45103

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Patches & Fixes for CVE-2026-45103 (2)

Vendor Advisories for CVE-2026-45103 (1)

Same Patch Batch · OpenSIPS · 2026-08-04 · 8 CVEs total

CVE-2026-45538 9.8 CRITICAL OpenSIPS: Stack Buffer Overflow in sip_to_json() Header Name Copy
CVE-2026-45100 9.1 CRITICAL OpenSIPS: Buffer Overflow in Base64 Encode Transformation
CVE-2026-45537 9.1 CRITICAL OpenSIPS: Global Buffer Overflow in construct_uri
CVE-2026-45084 8.7 HIGH OpenSIPS: Denial of service in presence.handle_publish() from unchecked Content-Type state
CVE-2026-45809 8.7 HIGH OpenSIPS: Denial of Service in watcherinfo XML generation from oversized watcher URI
CVE-2026-46334 8.7 HIGH OpenSIPS: Denial of Service in SDP bandwidth parsing via QoS SDP cloning
CVE-2026-45705 5.3 MEDIUM OpenSIPS: OOB Read in Multipart Body Boundary Parsing

IV. Related Vulnerabilities

Same product: opensips
Same vendor: OpenSIPS
Same weakness: CWE-190

V. Comments for CVE-2026-45103

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