Out-of-bounds Read in Emqx Nanomq
CVE-2026-21888
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.
Vulnerability class: Buffer Overflow
EPSS: 0.003 (22.5th 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
- Emqx Nanomq
- Nanomq — versions <= 0.24.6
Weakness classification (CWE)
References
- security-advisories@github.com (x_refsource_CONFIRM, Exploit, Vendor Advisory)
- security-advisories@github.com (x_refsource_MISC, Issue Tracking)
Frequently asked questions
- What is CVE-2026-21888?
- CVE-2026-21888 is a high-severity vulnerability in Emqx Nanomq, classified under Out-of-bounds Read. CVSS score: 7.5/10. Published 2026-03-11.
- How severe is CVE-2026-21888?
- High severity. CVSS v3 base score is 7.5 out of 10.