Vulnerability Details CVE-2026-67407
RabbitMQ is a messaging and streaming broker. From 4.0.0 until 4.3.3 and 4.2.9 and 4.1.14 and 4.0.23, Incomplete fix for CVE-2026-44838: escaperegexchar/1 does not escape -, leaving room for an MQTT topic permission bypass. the CVE-2026-44838 fix made expandtopicpermission/2 escape regex metacharacters in expanded topic-permission variables (escaperegex(V)), but escaperegexchar/1 escapes \ ^ $ . | ? + ( ) [ ] { } and omits -. When a topic permission template places {clientid} inside a [...] character class A low-privileged authenticated MQTT user controlling its clientid can broaden topic authorization (read and write) when templates embed {clientid} in a [...] This issue is fixed in versions 4.3.3 and 4.2.9 and 4.1.14 and 4.0.23.
Exploit prediction scoring system (EPSS) score
EPSS Score 0.002
EPSS Ranking 12.4%
CVSS Severity
CVSS v3 Score 7.1
References
Products affected by CVE-2026-67407
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cpe:2.3:a:broadcom:rabbitmq_server:4.0.0
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cpe:2.3:a:broadcom:rabbitmq_server:4.0.1
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cpe:2.3:a:broadcom:rabbitmq_server:4.0.13
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cpe:2.3:a:broadcom:rabbitmq_server:4.0.2
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cpe:2.3:a:broadcom:rabbitmq_server:4.0.20
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cpe:2.3:a:broadcom:rabbitmq_server:4.0.22
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cpe:2.3:a:broadcom:rabbitmq_server:4.0.3
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cpe:2.3:a:broadcom:rabbitmq_server:4.0.4
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cpe:2.3:a:broadcom:rabbitmq_server:4.0.5
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cpe:2.3:a:broadcom:rabbitmq_server:4.0.6
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cpe:2.3:a:broadcom:rabbitmq_server:4.0.7
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cpe:2.3:a:broadcom:rabbitmq_server:4.0.8
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cpe:2.3:a:broadcom:rabbitmq_server:4.0.9
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cpe:2.3:a:broadcom:rabbitmq_server:4.1.0
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cpe:2.3:a:broadcom:rabbitmq_server:4.1.1
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cpe:2.3:a:broadcom:rabbitmq_server:4.1.11
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cpe:2.3:a:broadcom:rabbitmq_server:4.1.2
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cpe:2.3:a:broadcom:rabbitmq_server:4.1.3
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cpe:2.3:a:broadcom:rabbitmq_server:4.1.4
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cpe:2.3:a:broadcom:rabbitmq_server:4.1.5
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cpe:2.3:a:broadcom:rabbitmq_server:4.1.6
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cpe:2.3:a:broadcom:rabbitmq_server:4.1.7
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cpe:2.3:a:broadcom:rabbitmq_server:4.1.8
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cpe:2.3:a:broadcom:rabbitmq_server:4.2.0
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cpe:2.3:a:broadcom:rabbitmq_server:4.2.1
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cpe:2.3:a:broadcom:rabbitmq_server:4.2.2
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cpe:2.3:a:broadcom:rabbitmq_server:4.2.3
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cpe:2.3:a:broadcom:rabbitmq_server:4.2.4
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cpe:2.3:a:broadcom:rabbitmq_server:4.2.5
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cpe:2.3:a:broadcom:rabbitmq_server:4.2.6
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cpe:2.3:a:broadcom:rabbitmq_server:4.2.7
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cpe:2.3:a:broadcom:rabbitmq_server:4.2.8
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cpe:2.3:a:broadcom:rabbitmq_server:4.3.0
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cpe:2.3:a:broadcom:rabbitmq_server:4.3.1
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cpe:2.3:a:broadcom:rabbitmq_server:4.3.2