---
id: "CVE-2026-106803"
kind: "vulnerability"
aliases: ["CVE-2026-106803"]
title: "Kamailio: crafted NOTIFY message overflows stack and crashes P-CSCF"
severity: "high"
cvss: null
epss: null
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["ims", "kamailio", "runtime", "sip", "voip"]
not_affected_if: ["module-not-loaded", "other-kamailio-versions"]
published_at: "2026-11-02T17:17:33+00:00"
first_seen_at: "2026-11-02T17:24:12+00:00"
updated_at: "2026-11-02T17:26:28+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-106803", "first_seen_at": "2026-11-02T17:24:12+00:00"}]
---

# Kamailio: crafted NOTIFY message overflows stack and crashes P-CSCF

Kamailio's ims_registrar_pcscf module copies an attacker-supplied port from a NOTIFY message's alias parameter into a fixed 5-byte stack buffer without a length check. An unauthenticated remote attacker can corrupt the stack and terminate the P-CSCF process, causing denial of service.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Check the installed Kamailio version with `kamailio -v`; versions 6.1.3 and 6.1.4 are affected.
- Check whether the ims_registrar_pcscf module is loaded in the Kamailio configuration.

## Fix

- Patch link is listed in the sources but the fixed version is unknown.

## Timeline

- 2026-11-02T17:24:12+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-106803

## Documents

- [fix] Patch: github.com https://github.com/kamailio/kamailio/commit/21261436492f0014930e804e20586e3833bb91b9

## From the sources

A stack-based buffer overflow exists in Kamailio v6.1.3 and v6.1.4 in the ims_registrar_pcscf module. When processing a crafted application/reginfo+xml NOTIFY message, process_contact() copies an attacker-controlled port value from the alias parameter into a fixed 5-byte stack buffer without validating its length. An unauthenticated remote attacker can trigger stack corruption and terminate the P-CSCF process, resulting in denial of service.

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_