What’s Vulnerable › Vulnerabilities

CVE-2026-44639: NanoMQ: O(N²) Denial of Service in MQTT v5 Property Parsing

• Severity: low (CVSS 3.7 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-18 · updated 2026-09-18
• Weakness: CWE-407

Description

NanoMQ is an MQTT broker. Prior to 0.24.14, NanoMQ's MQTT v5 property decoder in nng/src/supplemental/mqtt/mqtt_codec.c uses property_append() to walk the entire linked list for each property added by decode_buf_properties(). A remote unauthenticated client can supply a PUBLISH or SUBSCRIBE packet containing many User Properties, causing O(N²) linked-list insertion and CPU work that makes the broker unresponsive; repeated packets can sustain the denial of service. This issue is fixed in version 0.24.14.

Affected products

• nanomq: before 0.24.14

References

• https://github.com/nanomq/NanoNNG/commit/91bd4c7f45f945a3f5f0e37c459157dc7c277a07
• https://github.com/nanomq/NanoNNG/pull/1508
• https://github.com/nanomq/nanomq/releases/tag/0.24.14
• https://github.com/nanomq/nanomq/security/advisories/GHSA-6mwg-445v-2qrv
• https://github.com/nanomq/nanomq/security/advisories/GHSA-6mwg-445v-2qrv

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