---
id: CVE-2026-114550
title: >-
  libwebsockets MQTT Protocol PUBACK Packet Handling Out-Of-Bounds Write Remote
  Code Execution Vulnerability
summary: >-
  libwebsockets MQTT Protocol PUBACK Packet Handling Out-Of-Bounds Write Remote
  Code Execution Vulnerability. This vulnerability allows remote attackers to
  execute arbitrary code on affected installations of libwebsockets.
  Authentication i…
severity: high
cvss: 8.1
cvssVector: 'CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H'
cvssSource: cna
cwe:
  - CWE-787
vendor: libwebsockets
product: libwebsockets
affected:
  - libwebsockets b4b5aed3903eaff09cd76a410f69bbe5dff66f8e
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-11-06T18:54:55.995464Z'
exploitAvailable: true
published: '2026-11-03'
updated: '2026-11-06'
sourceUpdated: '2026-11-06T18:55:07.231Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-114550'
references:
  - url: 'https://www.zerodayinitiative.com/advisories/ZDI-26-792/'
    label: ZDI-26-792
  - url: >-
      https://github.com/warmcat/libwebsockets/commit/c9e8e1834d7f13038c82963086b90e2ee9c5b44c
    label: vendor-provided URL
tags:
  - cve.org
  - exploit-available
epss: 0.00842
epssPercentile: 0.58157
exploits:
  github: 1
  githubRepos:
    - 'https://github.com/googlesky/CVE-2026-114550'
  checkedAt: '2026-11-07T18:05:33.731Z'
zeroDay: true
ingestedAt: '2026-11-05T20:33:06.622Z'
---

## Overview

libwebsockets MQTT Protocol PUBACK Packet Handling Out-Of-Bounds Write Remote Code Execution Vulnerability. This vulnerability allows remote attackers to execute arbitrary code on affected installations of libwebsockets. Authentication is not required to exploit this vulnerability.

The specific flaw exists within the handling of PUBACK packets. The issue results from the lack of proper validation of user-supplied data, which can result in a write past the end of an allocated buffer. An attacker can leverage this vulnerability to execute code in the context of the current process. Was ZDI-CAN-31039.

## Affected

- `libwebsockets b4b5aed3903eaff09cd76a410f69bbe5dff66f8e`

## Remediation

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