CVE-2026-8686

DoS from MQTT v5.0 Deserialization Fault in core MQTT

State: Published
Severity: 8.7 High
Published: May 15, 2026
Updated: May 15, 2026
Reserved: May 15, 2026

Description

Missing bounds validation in the MQTT v5.0 property parser in coreMQTT before 5.0.1 allows an MQTT broker to cause a denial of service by sending a crafted packet.

To remediate this issue, users should upgrade to v5.0.1.

Scores

CVSS	Score	Vector	Source
4.0	8.7 High	CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N	AMZN
3.1	7.5 High	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H	AMZN

Weaknesses

CWE-125 Out-of-bounds read

Affected Products

Product	Versions
coreMQTTFreeRTOS	5.0.0Affected

References

https://github.com/FreeRTOS/coreMQTT/releases/tag/v5.0.1patch
https://aws.amazon.com/security/security-bulletins/2026-032-aws/vendor-advisory
https://github.com/FreeRTOS/coreMQTT/security/advisories/GHSA-6qh9-r6jp-2wxcthird-party-advisory

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