What’s Vulnerable › Vulnerabilities

CVE-2021-34431

• Severity: medium (CVSS 6.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.1% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2021-07-22 · updated 2026-06-17
• Weakness: CWE-401

Description

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.

Affected products

• The Eclipse Foundation Eclipse Mosquitto: from 1.6 through 2.0.10

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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