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 unbounded copying of SIP header names into a fixed-size buffer, allowing remote code execution via crafted SIP messages.
Exploitability: Exploitation requires sending a single UDP packet with a long header name; preconditions include the target using an affected version and having routing scripts that call sip_to_json().
Blast radius: If exploited, this can lead to process crashes or remote code execution on vulnerable deployments.
Prioritized remediation: Upgrade OpenSIPS to a non-affected version immediately.

rcebuffer-overflowsipudp

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.