CVE-2025-56352

HIGH EPSS 19.6%
Published May 18, 20261mo ago · Modified Jun 17, 20262w ago
7.5 CVSS 3.1
High
Find Similar
Published May 18, 2026 1mo ago
Last Modified Jun 17, 2026 2w ago

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.

CVSS Details

Base Score
7.5
Exploitability
3.9
Impact
3.6
Vector string
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack Vector Network
Attack Complexity Low
Privileges Required None
User Interaction None
Scope Unchanged
Confidentiality None
Integrity None
Availability High

Threat Intelligence

EPSS Exploit Probability
19.6% percentile
Exploit & Patch Status
No Known Exploit
No Patch Available

Weaknesses 1

CWE-400 Uncontrolled Resource Consumption Resource Mgmt

References 2

  • github.com https://github.com/JustDoIt0910/tinyMQTT/issues/19
  • github.com https://github.com/user-attachments/files/21207896/Resource_Exhaustion_Poc.txt

Remediation

No remediation data recorded yet

Check vendor advisories and the NVD entry for patch availability.