CVE Catalog

CVE-2025-56352

High
Published: Translated: NVD NIST

Summary

In tinyMQTT, due to a bug in handling CONNECT packets, the broker fails to close the TCP connection after receiving a packet with a zero-length Client ID when CleanSession is set to 0. This leads to server resource exhaustion with repeated connection attempts.

Risk Assessment

The organization may experience denial of service due to server resource exhaustion, which can impact the availability of services relying on the MQTT broker.

Recommendation

It is recommended to update to the latest version of tinyMQTT to fix this issue and to monitor TCP connections to detect and mitigate invalid connection attempts.

Related vulnerabilities

Original NVD description (English source)

In tinyMQTT commit 6226ade15bd4f97be2d196352e64dd10937c1962 (2024-02-18), the broker mishandles protocol violations during CONNECT packet parsing. When receiving a CONNECT packet with a zero-length Client ID while CleanSession is set to 0, the broker correctly replies with a CONNACK return code 0x02 (Identifier Rejected) but fails to explicitly close the TCP connection. Since the surrounding connection teardown logic is not guaranteed to execute, each such invalid CONNECT attempt leaves the underlying socket open. Repeated attempts cause server-side resource exhaustion due to accumulating file descriptors and memory usage, potentially resulting in denial of service.

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