Is CVE-2025-56352 actively exploited?

No active exploitation of CVE-2025-56352 has been confirmed so far. Continue monitoring, as exploit status can change.

Can CVE-2025-56352 be exploited remotely?

Yes. CVE-2025-56352 is exploitable remotely over the network (CVSS attack vector: Network).

What is the CVSS score of CVE-2025-56352?

CVE-2025-56352 has a CVSS score of 7.5 (HIGH).

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HIGH

CVE-2025-56352

CWE-400Published: May 18, 2026· Updated: May 18, 2026

7.5

CVSS v3.1

EPSS:0.05%probability of exploitation in 30 daysPercentile:16.0th

Official Description

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.

NVD Source

Technical Analysis

CVE-2025-56352 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A successful exploit results in availability disruption (denial of service), with a CVSS base score of 7.5.