CVE-2026-21888

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

State: Published
Severity: 7.5 High
Published: Mar 11, 2026
Updated: Mar 11, 2026
Reserved: Jan 5, 2026

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.

Scores

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

Weaknesses

CWE-125 Out-of-bounds Read

Affected Products

Product	Versions
nanomqnanomq	<= 0.24.6Affected

References

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

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