Input validation error in RabbitMQ Server - #VU143935
Published: August 18, 2026
Vulnerability identifier: #VU143935
CSH Severity: Low
CVSS v4: 5.3 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N]
CVE-ID: N/A
CWE-ID: CWE-20
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote user to cause a denial of service.
The vulnerability exists due to improper input validation in the MQTT 5 CONNECT property parser and MQTT prefetch handling when processing a CONNECT packet with a zero Receive Maximum value for a QoS 1 subscription on a classic queue. A remote user can send a specially crafted CONNECT packet, subscribe to a topic at QoS 1, and withhold PUBACK frames to cause a denial of service.
Exploitation requires valid credentials, permission to consume a topic, an enabled MQTT or Web MQTT listener, available QoS 1 messages, and a classic queue-backed subscription.
Affected software
RabbitMQ Server
Remediation
Install security update from vendor's website.
RabbitMQ Server - addressed in versions 4.2.10, 4.3.5