NanoMQ, an MQTT broker for edge messaging, has a type confusion flaw in the QUIC dialer close path. During a connection establishment the internal pointer is stored as an nni_quic_conn*, but later the close routine interprets it as an ex_quic_conn*. The mismatch leads the broker to dereference an invalid object, causing the close operation to hang or crash the process. This results in a lossy denial‑of‑service condition for the broker but does not allow code execution or data exfiltration.

The issue affects all NanoMQ releases older than 0.24.14, distributed by the nanomq vendor. There are no further vendor or product details beyond the NanoMQ package itself. Users on any platform running the affected broker should update.

The CVSS score of 4.5 places the vulnerability in the moderate range, while the EPSS score is not available, making the likelihood of exploitation uncertain. The vulnerability is not listed in CISA’s KEV catalog, and no public exploitation has been reported. The attack vector is inferred to be local or remote within the broker’s control plane, requiring an entity able to initiate or close QUIC connections. The known fix or upgrade to version 0.24.14 eliminates the flaw, negating the threat.