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
Published · last modified .
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.
EPSS exploit prediction
EPSS: 0.003 (20.6th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 21st percentile — 20.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: 0.000
Affected products
- Emqx Nanomq
- Nanomq — versions <= 0.24.6
Weakness classification (CWE)
References
- github.com/nanomq/nanomq/security/advisories/GHSA-cggc-6m7w-j7x5 (Exploit, Vendor Advisory)
- github.com/nanomq/nanomq/issues/2192 (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.