Resource exhaustion in Broadcom Rabbitmq Server
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.
Vulnerability class: DoS (Denial of Service)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.005 (45.9th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 46th percentile — 45.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.005 · change: +0.002
Affected products
- Broadcom Rabbitmq Server
- Rabbitmq Rabbitmq-Server — versions >= 3.13.0, < 3.13.15, >= 4.0.0, < 4.0.22, >= 4.1.0, < 4.1.11
Weakness classification (CWE)
References
- https://github.com/rabbitmq/rabbitmq-server/security/advisories/GHSA-89p2-f5cv-x5cg (Exploit, Third Party Advisory)
- https://github.com/rabbitmq/rabbitmq-server/commit/9a44124d9c932d6fc7d2a3b945e5a143e547bcb6 (Patch)
- https://github.com/rabbitmq/rabbitmq-server/commit/c5690583a53789a3bf00cca508b43e8246db0d11 (Patch)
- https://github.com/rabbitmq/rabbitmq-server/releases/tag/v4.2.6 (Release Notes)
- https://github.com/rabbitmq/rabbitmq-server/releases/tag/v4.3.1 (Release Notes)
Frequently asked questions
- What is CVE-2026-66071?
- CVE-2026-66071 is a medium-severity vulnerability in Broadcom Rabbitmq Server, classified under Uncontrolled Resource Consumption. CVSS score: 6.5/10. Published 2026-09-25.
- How severe is CVE-2026-66071?
- Medium severity. CVSS v3 base score is 6.5 out of 10.