What’s Vulnerable › Vulnerabilities

CVE-2026-25627: nanomq: OOB Read / Crash (DoS) via Malformed MQTT Remaining Length over WebSocket

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-03-30 · updated 2026-06-17
• Weakness: CWE-125

Description

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.

Affected products

• nanomq: before 0.24.8 — fixed in 0.24.8

How to fix

Upgrade to a fixed version: nanomq 0.24.8. Check the vendor advisory for mitigations.

References

• https://github.com/nanomq/NanoNNG/commit/e80b30bad6d855593a68d18f2785bfaca6faf09e
• https://github.com/nanomq/NanoNNG/pull/1405
• https://github.com/nanomq/nanomq/releases/tag/0.24.8
• https://github.com/nanomq/nanomq/security/advisories/GHSA-w4rh-v3h2-j29x
• https://github.com/nanomq/nanomq/security/advisories/GHSA-w4rh-v3h2-j29x

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