Out-of-bounds Read in Emqx Nanomq
CVE-2026-25627
NanoMQ MQTT Broker (NanoMQ) is an all-around Edge Messaging Platform. Prior to version 0.24.8, NanoMQ’s MQTT-over-WebSocket transport can be crashed by sending an MQTT packet with a deliberately large Remaining Length in the fixed header while providing a much shorter actual payload. The code path copies Remaining Length bytes without verifying that the current receive buffer contains that many bytes, resulting in an out-of-bounds read (ASAN reports OOB / crash). This is remotely triggerable over the WebSocket listener. This issue has been patched in version 0.24.8.
Vulnerability class: Buffer Overflow
Published · last modified .
CVSS v3 metric
CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.006 (47.2th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 47th percentile — 47.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.005 · newest: 0.006 · change: +0.001
Affected products
- Emqx Nanomq
- Nanomq — versions < 0.24.8
Weakness classification (CWE)
References
- github.com/nanomq/nanomq/security/advisories/GHSA-w4rh-v3h2-j29x (Exploit, Vendor Advisory)
- github.com/nanomq/NanoNNG/pull/1405 (Patch, Issue Tracking)
- github.com/nanomq/NanoNNG/commit/e80b30bad6d855593a68d18f2785bfaca6faf09e (Patch)
- github.com/nanomq/nanomq/releases/tag/0.24.8 (Release Notes)
Frequently asked questions
- What is CVE-2026-25627?
- CVE-2026-25627 is a medium-severity vulnerability in Emqx Nanomq, classified under Out-of-bounds Read. CVSS score: 6.5/10. Published 2026-03-30.
- How severe is CVE-2026-25627?
- Medium severity. CVSS v3 base score is 6.5 out of 10.