What’s Vulnerable › Vulnerabilities

CVE-2026-61633: NanoMQ: Infinite Loop in UNSUBSCRIBE Decoder Leading to Remote DoS

• Severity: low (CVSS 2.0 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% 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-835

Description

NanoMQ is an MQTT broker. Prior to 0.24.14, the NanoMQ client function nni_mqtt_msg_decode_unsubscribe() in nng/src/supplemental/mqtt/mqtt_codec.c does not handle a failed read_uint16() while counting topics in a malformed UNSUBSCRIBE packet. A zero-length topic followed by trailing data can leave buf.curpos unchanged while topic_count continues to increase, allowing a malicious MQTT broker to hang a connecting MQTT 3.1.1 client, consume CPU and memory, and repeatedly deny service when automatic reconnection is enabled. The broker-side nmq_unsubinfo_decode path is not affected. This issue is fixed in version 0.24.14.

Affected products

• nanomq: before 0.24.14

References

• https://github.com/nanomq/NanoNNG/commit/fa8d859bb39841e46cfc6cce280d242bd782ad3d
• https://github.com/nanomq/NanoNNG/pull/1518
• https://github.com/nanomq/nanomq/releases/tag/0.24.14
• https://github.com/nanomq/nanomq/security/advisories/GHSA-m7mp-rr3v-hmhr
• https://github.com/nanomq/nanomq/security/advisories/GHSA-m7mp-rr3v-hmhr

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