NanoMQ: O(N²) Denial of Service in MQTT v5 Property Parsing

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.

Scores

EPSS (exploitation in 30 days)

0.44% · top 61% of all CVEs (6 Nov 2026)

CISA SSVC

Exploitation: poc · Automatable: no · Technical impact: partial

The list uses the assigner's score when there is one, then CISA's, then NVD's: Low 3.7.

Weakness

• CWE-407: Inefficient Algorithmic Complexity (opens in a new tab)All about CWE-407 and its CVEs

Affected products

• nanomq · nanomq

  • affected < 0.24.14

References (4)

• https://github.com/nanomq/nanomq/security/advisories/GHSA-6mwg-445v-2qrv (opens in a new tab)x_refsource_CONFIRMexploit
• https://github.com/nanomq/NanoNNG/pull/1508 (opens in a new tab)x_refsource_MISC
• https://github.com/nanomq/NanoNNG/commit/91bd4c7f45f945a3f5f0e37c459157dc7c277a07 (opens in a new tab)x_refsource_MISC
• https://github.com/nanomq/nanomq/releases/tag/0.24.14 (opens in a new tab)x_refsource_MISC

Sources

The same CVE in the primary databases and aggregators, to check against.

• CVE.org record (opens in a new tab)
• CVE List JSON (GitHub) (opens in a new tab)
• NVD (opens in a new tab)
• FIRST EPSS (opens in a new tab)
• OSV.dev (opens in a new tab)
• GitHub Advisories (opens in a new tab)
• CIRCL Vulnerability-Lookup (opens in a new tab)

Badge for a README or a ticket

[![CVE-2026-44639](https://trackcve.app/badge/CVE-2026-44639.svg)](https://trackcve.app/cve/CVE-2026-44639)

Record last updated 18 Sept 2026, 17:21 UTC.