---
id: CVE-2026-45809
title: OpenSIPS is a Session Initiation Protocol (SIP) server implementation
summary: >-
  OpenSIPS is a Session Initiation Protocol (SIP) server implementation.
  Versions prior to 3.6.6 and 4.0.0-rc1 contain a denial of service
  vulnerability in the watcherinfo generation functionality. An attacker can
  create an oversized watch…
severity: none
cwe:
  - CWE-121
published: '2026-08-05'
updated: '2026-09-08'
sourceUpdated: '2026-09-08T20:41:31.497'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-45809'
references:
  - url: >-
      https://github.com/OpenSIPS/opensips/commit/c5970d3ee25b457ad2d78fe6e9662a12dae577cd
    label: security-advisories@github.com
  - url: >-
      https://github.com/OpenSIPS/opensips/commit/dd86461b71ff4a4f5194205896ae5f48f144240d
    label: security-advisories@github.com
  - url: >-
      https://github.com/OpenSIPS/opensips/security/advisories/GHSA-gx83-2gh8-7v56
    label: security-advisories@github.com
  - url: >-
      https://github.com/OpenSIPS/opensips/security/advisories/GHSA-gx83-2gh8-7v56
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
tags:
  - nvd
epss: 0.00388
epssPercentile: 0.32666
ingestedAt: '2026-09-08T21:11:12.267Z'
---

## Overview

OpenSIPS is a Session Initiation Protocol (SIP) server implementation. Versions prior to 3.6.6 and 4.0.0-rc1 contain a denial of service vulnerability in the watcherinfo generation functionality. An attacker can create an oversized watcher entry by sending a SUBSCRIBE Event: presence request with a long From URI, and then trigger presence.winfo watcherinfo XML generation for the same presentity. OpenSIPS copies the stored watcher URI into a fixed-size stack buffer, overflowing it and crashing the process. A remote attacker can crash an OpenSIPS worker in deployments that expose handle_subscribe() and allow watcherinfo (presence.winfo) generation. The issue is configuration-dependent because the presence and presence_xml modules must be loaded and SUBSCRIBE routing must be reachable. This issue has been fixed in versions 3.6.6 and 4.0.0-rc1.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.