CVE-2021-34431

6.5 mediumEPSS 1.1%

Medium (6.5) in eclipse mosquitto. EPSS 1.1% chance of exploitation in the next 30 days.

In Eclipse Mosquitto version 1.6 to 2.0.10, if an authenticated client that had connected with MQTT v5 sent a crafted CONNECT message to the broker a memory leak would occur, which could be used to provide a DoS attack against the broker.

Severity

CVSS 3.1

6.5 medium

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

EPSS: 1.1% chance of exploitation in the next 30 days; higher than 66% of CVEs (scores of 2026-10-31)
CWE: CWE-401
Published: 2021-07-22
Modified: 2026-06-17
Record from: the NVD, synced 2026-10-19

Affected

eclipse:mosquitto

References

https://bugs.eclipse.org/bugs/show_bug.cgi?id=573191
https://bugs.eclipse.org/bugs/show_bug.cgi?id=573191

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