Vulnerability Details CVE-2026-66071
RabbitMQ is a messaging and streaming broker. From 3.13.0 until 3.13.15 and 4.0.22 and 4.1.11 and 4.2.6 and 4.3.1, Atom exhaustion: OAuth2 JWT tag: scope values. extractscopes/1 parses scopes of the form .tag: and calls rabbitdatacoercion:toatom() to convert to a tag atom. The token signature is verified first, so the attacker cannot forge scopes , but in IdP configurations where scope content is user-influenced, each login with a novel tag value leaks one In deployments where users can influence the scopes included in their IdP-issued JWT rabbitmqauthbackendoauth2 enabled IdP permits attacker-influenced scope values in signed tokens. This issue is fixed in versions 3.13.15 and 4.0.22 and 4.1.11 and 4.2.6 and 4.3.1.
Exploit prediction scoring system (EPSS) score
EPSS Score 0.003
EPSS Ranking 26.1%
CVSS Severity
CVSS v3 Score 6.5
References
- https://github.com/rabbitmq/rabbitmq-server/commit/9a44124d9c932d6fc7d2a3b945e5a143e547bcb6
- https://github.com/rabbitmq/rabbitmq-server/commit/c5690583a53789a3bf00cca508b43e8246db0d11
- https://github.com/rabbitmq/rabbitmq-server/releases/tag/v4.2.6
- https://github.com/rabbitmq/rabbitmq-server/releases/tag/v4.3.1
- https://github.com/rabbitmq/rabbitmq-server/security/advisories/GHSA-89p2-f5cv-x5cg
Products affected by CVE-2026-66071
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cpe:2.3:a:broadcom:rabbitmq_server:3.13.0
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cpe:2.3:a:broadcom:rabbitmq_server:3.13.1
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cpe:2.3:a:broadcom:rabbitmq_server:3.13.2
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cpe:2.3:a:broadcom:rabbitmq_server:3.13.3
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cpe:2.3:a:broadcom:rabbitmq_server:3.13.4
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cpe:2.3:a:broadcom:rabbitmq_server:3.13.5
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cpe:2.3:a:broadcom:rabbitmq_server:3.13.6
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cpe:2.3:a:broadcom:rabbitmq_server:3.13.7
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cpe:2.3:a:broadcom:rabbitmq_server:3.13.9
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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:4.0.3
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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:4.1.2
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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