CVE-2026-45538

9.8 CRITICALpublic exploit available

Published 2026-08-04 · Updated 2026-08-05

AI risk analysis

Summary: The flaw is a stack buffer overflow in OpenSIPS due to improper handling of SIP header names, allowing remote attackers to crash the process or achieve remote code execution.
Exploitability: Exploitation is relatively easy with a single unauthenticated UDP packet, requiring a SIP message with a header name longer than 255 bytes.
Blast radius: If exploited, this can lead to process crashes or remote code execution, impacting any deployment whose routing script invokes sip_to_json().
Detection: No reliable host or network indicator is derivable from the published description.
Prioritized remediation: Upgrade to OpenSIPS 4.1.0 or later.

rcestack-overflowsipbuffer-overflow

Analysis generated locally by qwen2.5:7b-instruct (no data left the box). AI-assisted — verify against primary sources before acting.

NVD description

OpenSIPS is a Session Initiation Protocol (SIP) server implementation. In versions 4.0.0 and prior, processing a SIP message with a header name longer than 255 bytes causes a stack buffer overflow when sip_to_json() is called in the routing script. Function sip_to_json() (modules/sipmsgops/sipmsgops.c) copies SIP header names into a fixed 255-byte stack buffer without bounds checking, performing a memcpy of the full header-name length even though the SIP parser imposes no such limit (a header name can be roughly 65000 bytes). As a result, when a routing script calls sip_to_json(), a SIP message with a header name longer than 255 bytes triggers a stack buffer overflow in which both the length and content of the overwrite are attacker-controlled, corrupting the saved frame pointer and return address. A single unauthenticated UDP packet to the SIP port (5060) can crash the process or, on builds without stack protections, hijack the return address to achieve remote code execution. This affects deployments whose routing script invokes sip_to_json(). This issue was not fixed at the time of publication.

CVSS vector

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

Weaknesses

CWE-121

Public exploit & PoC references

All references

Source data: NVD (nvd.nist.gov), public domain. Exploit-DB.ai adds local AI analysis for defensive use only.

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