CVE Catalog

CVE-2026-30867

MediumCVSS 5.7
Published: Updated: Translated: NVD NIST

Exploitation Probability (EPSS)

Low risk
0.32%

25th percentile - higher than 25% of all known CVEs

Summary

CocoaMQTT before 2.2.2 has a packet parsing vulnerability that allows an attacker (or compromised MQTT broker) to remotely crash the host iOS/macOS/tvOS application. If an attacker publishes a 4-byte malformed payload to a shared topic with RETAIN set, the broker persists it and automatically pushes it to any subscribing client, instantly crashing the app in the background. Fixed in 2.2.2.

Risk Assessment

This can cause a persistent denial-of-service (app crash) until the retained message is manually wiped from the broker. It affects mobile app availability and can be used to intentionally block services.

Recommendation

Update CocoaMQTT to version 2.2.2 or later. Additionally, consider purging retained messages from the broker and implementing packet validation on the broker side.

Related vulnerabilities

Original NVD description (English source)

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.

Vulnerability data from NVD (NIST) · CISA KEV · EPSS