CVE-2025-56353

High

Description

In tinyMQTT commit 6226ade15bd4f97be2d196352e64dd10937c1962 (2024-02-18), a memory leak occurs due to the broker's failure to validate or reject malformed UTF-8 strings in topic filters. An attacker can exploit this by sending repeated subscription requests with arbitrarily large or invalid filter payloads. Each request causes memory to be allocated for the malformed topic filter, but the broker does not free the associated memory, leading to unbounded heap growth and potential denial of service under sustained attack.

SeverityHigh
CVSS7.5
Exploit probability—
ProductJustdoit0910 Tinymqtt
PublishedJan 20, 2026
First seenJan 20, 2026
Weakness typeCWE-401CWE-401

How to fix

Sources list no fixed version or patch link for this vulnerability.

Affected products

ProductAffected versionsFixed in
justdoit0910 tinymqtt2024-02-18—

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