CVE-2026-25627

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

HIGH
7.5
CVSS Score
Published: March 30, 2026 at 08:11 PM UTC
Updated: June 17, 2026 at 10:24 AM UTC
2 products affected across 2 vendorsNanomqNanomq

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Severity
HIGH7.5
Exploit prediction
EPSS 0.5%
SSVC
PoC

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

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 0.24.8
v < 0.24.8
Affected range stops below 0.24.8, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

References (4)

x_refsource_CONFIRMExploitVendor Advisory
Source: cverecord
https://github.com/nanomq/nanomq/security/advisories/GHSA-w4rh-v3h2-j29x
x_refsource_MISCIssue TrackingPatch
Source: cverecord
https://github.com/nanomq/NanoNNG/pull/1405
x_refsource_MISCRelease Notes
Source: cverecord
https://github.com/nanomq/nanomq/releases/tag/0.24.8

SSVC — Action Prioritization

SSVCPoCNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusANALYZED
CWE
CWE-125

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