CVE-2026-21888

Name: CVE-2026-21888
Creator: NVD / NIST
Published: 2026-03-11T16:16:23.93+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 7.5/10EPSS 0.30%

Last modified Jun 17, 2026

CVE-2026-21888 is a high-severity vulnerability rated 7.5/10 on the CVSS scale. NanoMQ MQTT Broker (NanoMQ) is an all-around Edge Messaging Platform. MQTT v5 Variable Byte Integer parsing out-of-bounds: get_var_integer() accepts 5-byte varints without bounds checks; reliably triggers OOB read / crash when built with ASan. EPSS estimates a 0.30% chance of exploitation in the next 30 days.

Description

NanoMQ MQTT Broker (NanoMQ) is an all-around Edge Messaging Platform. MQTT v5 Variable Byte Integer parsing out-of-bounds: get_var_integer() accepts 5-byte varints without bounds checks; reliably triggers OOB read / crash when built with ASan. This affects 0.24.6 and earlier.

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

0.30%

21.8th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-125

Affected Software

Vendor	Product	Versions
Emqx	Nanomq	<= 0.24.6

References

https://github.com/nanomq/nanomq/issues/2192Issue Tracking
https://github.com/nanomq/nanomq/security/advisories/GHSA-cggc-6m7w-j7x5Exploit, Vendor Advisory

Timeline

Published: Mar 11, 2026
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2026-21888?

How severe is CVE-2026-21888?

CVE-2026-21888 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 0.30% probability of exploitation in the next 30 days.

How do I fix CVE-2026-21888?

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-2026-21888?

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

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Source: NVD / NIST