Is CVE-2026-73863 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-73863 being exploited in the wild.

How severe is CVE-2026-73863?

Informational severity, published 18 September 2026.

Is there a fix for CVE-2026-73863?

A patch was published on 2026-05-20: Fix merged in PR #1518 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-73863 attacked?

It is attacked over the network, in a software library.

Am I affected by CVE-2026-73863?

Check whether you run 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.

CVE-2026-73863: NanoMQ heap buffer over-read in MQTT SUBSCRIBE parsing

CVE-2026-73863 · Severity: info · Published 2026-09-18

NanoMQ is an open-source MQTT message broker used for IoT and real-time messaging. A remote attacker can crash the broker by sending a malformed MQTT SUBSCRIBE packet, causing a denial of service. The vulnerability affects the broker's message parsing logic and allows an unauthenticated client to trigger a heap buffer over-read without requiring any special network conditions.

Vendors: NanoMQ.

Quick answers

Is CVE-2026-73863 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-73863 being exploited in the wild.
How severe is CVE-2026-73863?: Informational severity, published 18 September 2026.
Which products and versions are affected?: NanoMQ prior to 0.24.14.
Is there a fix for CVE-2026-73863?: A patch was published on 2026-05-20: Fix merged in PR #1518 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-73863 attacked?: It is attacked over the network, in a software library.
Am I affected by CVE-2026-73863?: Check whether you run 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

The nmq_subinfo_decode() function in mqtt_parser.c incorrectly reuses the outer Properties Length variable when parsing multiple SUBSCRIPTION_IDENTIFIER fields, causing get_var_integer() to read from an incorrect heap offset. An attacker sends a SUBSCRIBE packet with a multi-byte Properties Length and repeated subscription identifiers to trigger the over-read. The flaw is remotely exploitable and results in broker crash; a patch is available in version 0.24.14.

Affected products

NanoMQ NanoMQ prior to 0.24.14

Timeline

2026-09-18: disclosed
2026-05-20: patched: Fix merged in PR #1518

References

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