CVE-2025-56353

Published Jan 20, 2026 CVSS 3.1 · 7.5 High EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
CPEs cpe:2.3:a:justdoit0910:tinymqtt:2024-02-18:*:*:*:*:*:*:*
Type Values Removed Values Added
Weaknesses CWE-401
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}

ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Justdoit0910
Justdoit0910 tinymqtt
Vendors & Products Justdoit0910
Justdoit0910 tinymqtt
Type Values Removed Values Added
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.
References
Weaknesses

Sources

Status
PUBLISHED
Assigner
mitre
Published
Updated
Jan 21, 2026, 2:39 PM
Reserved
Aug 16, 2025, 12:00 AM
Status
Analyzed
Published
Jan 20, 2026, 4:16 PM
Modified
Jun 17, 2026, 9:42 AM