What is CVE-2026-8686?

CVE-2026-8686 is a high-severity vulnerability in Freertos Coremqtt, classified under Out-of-bounds Read. CVSS score: 7.5/10. Published 2026-05-15.

How severe is CVE-2026-8686?

High severity. CVSS v3 base score is 7.5 out of 10.

Out-of-bounds Read in Freertos Coremqtt

CVE-2026-8686

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.

Vulnerability class: Buffer Overflow

EPSS: 0.000 (8.4th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

Affected products

Freertos Coremqtt — versions 5.0.0

Weakness classification (CWE)

CWE-125 — Out-of-bounds Read

References

ff89ba41-3aa1-4d27-914a-91399e9639e5 (Release Notes, patch)
ff89ba41-3aa1-4d27-914a-91399e9639e5 (vendor-advisory, Vendor Advisory)
ff89ba41-3aa1-4d27-914a-91399e9639e5 (Vendor Advisory, third-party-advisory)

Frequently asked questions

What is CVE-2026-8686?: CVE-2026-8686 is a high-severity vulnerability in Freertos Coremqtt, classified under Out-of-bounds Read. CVSS score: 7.5/10. Published 2026-05-15.
How severe is CVE-2026-8686?: High severity. CVSS v3 base score is 7.5 out of 10.