# CVE-2026-114550: libwebsockets MQTT Protocol PUBACK Packet Handling Out-Of-Bounds Write Remote Code Execution Vulnerability

Status: published. Published: 2026-11-03. Updated: 2026-11-03.

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.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- libwebsockets / libwebsockets: b4b5aed3903eaff09cd76a410f69bbe5dff66f8e (affected). Source: CNA: zdi

## Severity and prioritization

- CVSS 3.0: 8.1 (high); CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H; source: CNA: zdi

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: Not available

- Weaknesses: CWE-787

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://www.zerodayinitiative.com/advisories/ZDI-26-792/ (CNA: zdi; x_research-advisory)

- https://github.com/warmcat/libwebsockets/commit/c9e8e1834d7f13038c82963086b90e2ee9c5b44c (CNA: zdi; vendor-advisory)

## Provenance

- CNA: zdi: https://www.cve.org/CVERecord?id=CVE-2026-114550; retrieved 2026-11-04; source updated 2026-11-03

Revision: 36ff27567822ab146a6164f859b1f7c281a840959bdb2791ebbe8729fd9b4dfb

Canonical: https://y2.dev/cve/CVE-2026-114550

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