# CVE-2026-47275: NanoMQ NULL pointer dereference in nni_mqttv5_msg_decode_connect

Source: https://junglewise.ai/threats/cve-2026-47275-nanomq-null-pointer-dereference-in-nni-mqttv5-msg-decode-connect  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-20. Updated: 2026-07-20  
License: CC BY 4.0 with a link back

CVE-2026-47275 · Severity: low · CVSS 2.6 · Published 2026-07-20

NanoMQ is a lightweight messaging engine used for communication between IoT devices. A vulnerability in how it handles certain messages allows a malicious server to crash the NanoMQ client or bridge. This can lead to a permanent loss of connectivity if the system enters a continuous crash-and-restart loop, disrupting data flow from IoT sensors or devices.

Technologies: [EMQ NanoMQ](https://junglewise.ai/threats/technologies/nanomq). Vendors: [EMQ](https://junglewise.ai/threats/vendors/emq).

## Quick answers

**Is CVE-2026-47275 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-47275 being exploited in the wild.

**How severe is CVE-2026-47275?** Low severity, with a CVSS score of 2.6, published 20 July 2026.

**Which products and versions are affected?** EMQ NanoMQ <= 0.24.11.

**Is there a fix for CVE-2026-47275?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-47275 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-47275?** Check whether you run EMQ NanoMQ at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A NULL pointer dereference exists in the `nni_mqttv5_msg_decode_connect()` function within `mqtt_codec.c`. The vulnerability is triggered when the decoder incorrectly uses the `prop` variable instead of `will_prop` while iterating over MQTTv5 CONNECT properties. If a packet contains 'will' properties but no connect-level properties, the code attempts to dereference a NULL pointer, leading to a SIGSEGV crash. This affects both the `nanomq_cli` and the core bridge mode. An attacker controlling a malicious broker can trigger this with a single 35-byte packet, potentially causing a persistent DoS via infinite crash loops during auto-reconnection.

## Affected products

- nanomq nanomq <= 0.24.11

## Timeline

- 2026-06-26: disclosed: Advisory published on GitHub
- 2026-07-20: advisory: CVE published to NVD

## References

- [https://github.com/nanomq/nanomq/security/advisories/GHSA-52qr-3v49-wmx6](https://github.com/nanomq/nanomq/security/advisories/GHSA-52qr-3v49-wmx6)

## Related threats

- [NanoMQ NULL pointer dereference in REST API properties_parse](https://junglewise.ai/threats/cve-2026-47276-nanomq-null-pointer-dereference-in-rest-api-properties-parse)
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- [NanoMQ type confusion in QUIC dialer close path](https://junglewise.ai/threats/cve-2026-44640-nanomq-type-confusion-in-quic-dialer-close-path)
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