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CVE-2025-56353

HIGHCVSS 7.5/10EPSS 0.29%

Last modified

CVE-2025-56353 is a high-severity vulnerability rated 7.5/10 on the CVSS scale. 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. EPSS estimates a 0.29% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1
7.5/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS Probability
0.29%

20.4th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

VendorProductVersions
Justdoit0910Tinymqtt2024-02-18

References

Timeline

Published
Last Modified
Status
Analyzed

Frequently Asked Questions

What is CVE-2025-56353?
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.
How severe is CVE-2025-56353?
CVE-2025-56353 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 0.29% probability of exploitation in the next 30 days.
How do I fix CVE-2025-56353?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2025-56353?

Run a free Strix scan to check your systems for this vulnerability.

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Source: NVD / NIST