CVE-2026-30867

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.

The following products are affected by CVE-2026-30867 vulnerability.

Here, you will find a curated list of external links that provide in-depth information to CVE-2026-30867.

URL	Resource
https://github.com/emqx/CocoaMQTT/commit/010bca6f61b97d726252f61641d331a2bf82b338
https://github.com/emqx/CocoaMQTT/pull/659
https://github.com/emqx/CocoaMQTT/releases/tag/2.2.2
https://github.com/emqx/CocoaMQTT/security/advisories/GHSA-r3fr-7m74-q7g2