CVE-2026-21888 PUBLISHED

MQTT v5 Variable Byte Integer parsing out-of-bounds: get_var_integer()

Assigner: GitHub_M
Reserved: 05.01.2026 Published: 11.03.2026 Updated: 11.03.2026

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

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS Score: 7.5

Attack Vector	Network	Scope	Unchanged
Attack Complexity	Low	Confidentiality Impact	None
Privileges Required	None	Integrity Impact	None
User Interaction	None	Availability Impact	High

CVSS 3.1

Product Status

Vendor	nanomq
Product	nanomq
Versions	Version <= 0.24.6 is affected

References

https://github.com/nanomq/nanomq/security/advisories/GHSA-cggc-6m7w-j7x5
https://github.com/nanomq/nanomq/issues/2192

Problem Types

CWE-125: Out-of-bounds Read CWE