Cyber Resilience

CVE-2026-8686

High

Published: 15 May 2026

Published
15 May 2026
Modified
19 May 2026
KEV Added
—
Patch
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CVSS Score v4 8.7 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
EPSS Score 0.0039 30.7th percentile
Risk Priority 55 floored blend · peak EPSS

Summary

CVE-2026-8686 is a high-severity Out-of-bounds Read (CWE-125) vulnerability in Freertos Coremqtt. Its CVSS base score is 8.7 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Application or System Exploitation (T1499.004); ranked at the 30.7th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

EU & UK References

Vulnerability details

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.

CWE(s)
CWE-125

Related Threats

MITRE ATT&CK Enterprise TechniquesAI

T1499.004 Application or System Exploitation Impact
Adversaries may exploit software vulnerabilities that can cause an application or system to crash and deny availability to users.
attack.mitre.org →
Why these techniques?

Out-of-bounds read in MQTT packet parser directly enables application-layer DoS via crafted network packet (T1499.004).

Confidence: HIGH · MITRE ATT&CK Enterprise v19.0

CVEs Like This One

CVE-2026-33096Shared CWE-125
CVE-2026-22023Shared CWE-125
CVE-2026-23456Shared CWE-125
CVE-2025-21598Shared CWE-125
CVE-2026-25627Shared CWE-125
CVE-2026-25942Shared CWE-125
CVE-2026-37535Shared CWE-125
CVE-2025-24265Shared CWE-125
CVE-2026-43006Shared CWE-125
CVE-2025-63650Shared CWE-125

Affected Assets

freertos
coremqtt
5.0.0

Mitigating Controls

No mitigating controls mapped yet. The per-CVE control annotator has not reached this CVE.

References