EUVD-2026-32548CVSS VectorNVD
CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:L/VA:L/SC:H/SI:H/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
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2DescriptionNVD
RabbitMQ is a messaging and streaming broker. From 4.2.0 to before 4.2.4, RabbitMQ's MQTT plugin allows for topic-level authorization using regular expressions with variable substitution. Administrators can create patterns such as ^{client_id}-sensors$ to restrict user access to topics that include their client ID. However, the client_id is provided by the user in the MQTT CONNECT packet and is inserted into the regex pattern without escaping special regex characters. This flaw enables an authenticated MQTT user to inject regex operators to bypass authorization. This vulnerability is fixed in 4.2.4 and 4.3.0.
AnalysisAI
{client_id}-sensors$', the unsanitized client_id value is embedded directly into the server-side regex, letting a crafted client_id (e.g., '.*' or 'legit|(admin)') alter the pattern's matching logic and grant access to topics the user should not reach. No public exploit has been identified at time of analysis, and the attack requires both valid MQTT credentials and a specifically configured authorization policy, but the high subsequent system impact (SC:H/SI:H per CVSS 4.0) elevates this beyond a simple medium-severity finding for affected deployments.
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