CVE-2026-21888 HIGH

CVE-2026-21888: MQTT v5 Variable Byte Integer parsing out-of-bounds: get_var_integer()

Vendor Nanomq
Product nanomq
Weakness CWE-125
Published March 11, 2026
Last update March 11, 2026
View on NVD All CVEs

CVSS base score

7.5/10
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Confidentiality None
Integrity None

CVSS vector

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

What the vulnerability does

01Description

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.

Key dates

02Disclosure timeline

March 11, 2026 CVE published
March 11, 2026 Record updated