PT-2026-29743 · Emqx · Cocoamqtt

Published 2026-04-02 · Updated 2026-04-02 · CVE-2026-30867

Mitre

CVSS v3.1

5.7

Medium

AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:H

CocoaMQTT is a MQTT 5.0 client library for iOS and macOS written in Swift. Prior to version 2.2.2, a vulnerability exists in the packet parsing logic of CocoaMQTT that allows an attacker (or a compromised/malicious MQTT broker) to remotely crash the host iOS/macOS/tvOS application. If an attacker publishes the 4-byte malformed payload to a shared topic with the RETAIN flag set to true, the MQTT broker will persist the payload. Any time a vulnerable client connects and subscribes to that topic, the broker will automatically push the malformed packet. The app will instantly crash in the background before the user can even interact with it. This effectively "bricks" the mobile application (a persistent DoS) until the retained message is manually wiped from the broker database. This issue has been patched in version 2.2.2.

Fix

Assertion Failure

Weakness Enumeration

CWE-617

Related Identifiers

CVE-2026-30867

Affected Products

Cocoamqtt

References · 5

• https://nvd.nist.gov/vuln/detail/CVE-2026-30867 · Security Note
• https://github.com/emqx/CocoaMQTT/pull/659 · Note
• https://github.com/emqx/CocoaMQTT/commit/010bca6f61b97d726252f61641d331a2bf82b338 · Note
• https://github.com/emqx/CocoaMQTT/releases/tag/2.2.2 · Note
• https://github.com/emqx/CocoaMQTT/security/advisories/GHSA-r3fr-7m74-q7g2 · Note