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Description

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.

PUBLISHED Reserved 2026-03-05 | Published 2026-04-02 | Updated 2026-04-02 | Assigner GitHub_M




MEDIUM: 5.7CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:H

Problem types

CWE-617: Reachable Assertion

Product status

< 2.2.2
affected

References

github.com/...oaMQTT/security/advisories/GHSA-r3fr-7m74-q7g2

github.com/emqx/CocoaMQTT/pull/659

github.com/...ommit/010bca6f61b97d726252f61641d331a2bf82b338

github.com/emqx/CocoaMQTT/releases/tag/2.2.2

cve.org (CVE-2026-30867)

nvd.nist.gov (CVE-2026-30867)

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