CVE-2026-114550

High

Description

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.

SeverityHigh

CVSS8.1

Exploit probability—

ProductLibwebsockets

PublishedNov 4, 2026

First seenNov 4, 2026

Weakness typeCWE-787Out-of-bounds write

How to fix

Vendor advisories

github.com/warmcat/libwebsockets/commit/c9e8e1834d7f13038c82963086b90e2ee9c5b44c

Affected products

Product	Affected versions	Fixed in
libwebsockets libwebsockets	b4b5aed3903eaff09cd76a410f69bbe5dff66f8e	—

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