EUVD-2026-18235
GHSA-r3fr-7m74-q7g2
CVSS Vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:H
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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.
Analysis
CocoaMQTT library versions prior to 2.2.2 allow remote denial of service when parsing malformed MQTT packets from a broker, causing immediate application crashes on iOS, macOS, and tvOS devices. An attacker or compromised MQTT broker can publish a 4-byte malformed payload with the RETAIN flag to persist it indefinitely, ensuring every vulnerable client that subscribes receives the crash-inducing packet, effectively bricking the application until manual intervention on the broker. …
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