Vulnerability 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.
CVSS Score
MEDIUM
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Emqx | Cocoamqtt | < 2.2.2 |
| Apple | Iphone Os | - |
| Apple | Macos | - |
Related Weaknesses (CWE)
References
- https://github.com/emqx/CocoaMQTT/commit/010bca6f61b97d726252f61641d331a2bf82b33Patch
- https://github.com/emqx/CocoaMQTT/pull/659Issue TrackingPatch
- https://github.com/emqx/CocoaMQTT/releases/tag/2.2.2Release Notes
- https://github.com/emqx/CocoaMQTT/security/advisories/GHSA-r3fr-7m74-q7g2ExploitVendor Advisory
FAQ
What is CVE-2026-30867?
CVE-2026-30867 is a vulnerability with a CVSS score of 5.7 (MEDIUM). 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 comprom...
How severe is CVE-2026-30867?
CVE-2026-30867 has been rated MEDIUM with a CVSS base score of 5.7/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-30867?
Check the references section above for vendor advisories and patch information. Affected products include: Emqx Cocoamqtt, Apple Iphone Os, Apple Macos.