Auth bypass in Broadcom Rabbitmq Server
CVE-2026-66078
RabbitMQ is a messaging and streaming broker. From 3.13.0 until 3.13.15 and 4.0.20 and 4.1.11 and 4.2.6, protected tag bypass via bulk-delete. dELETE /api/users/:name refuses to delete users tagged protected (rabbitmgmtwmuser:deleteresource/2 checks isprotecteduser). POST /api/users/bulk-delete iterates the supplied username list and calls rabbitauthbackendinternal:deleteuser/2 directly , that function has no protected-tag check , so the guard is silently An administrator can delete protected-tagged service accounts via the bulk endpoint, bypassing a safeguard the test suite confirms is rabbitmqmanagement enabled Attacker has the administrator tag A protected-tagged user. This issue is fixed in versions 3.13.15 and 4.0.20 and 4.1.11 and 4.2.6.
Vulnerability class: Broken Access Control
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:L/A:H.
EPSS exploit prediction
EPSS: 0.004 (37.5th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 38th percentile — 37.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.004 · newest: 0.004 · change: +0.001
Affected products
- Broadcom Rabbitmq Server
- Rabbitmq Rabbitmq-Server — versions >= 3.13.0, < 3.13.15, >= 4.0.0, < 4.0.20, >= 4.1.0, < 4.1.11
Weakness classification (CWE)
References
Frequently asked questions
- What is CVE-2026-66078?
- CVE-2026-66078 is a medium-severity vulnerability in Broadcom Rabbitmq Server, classified under Missing Authorization. CVSS score: 5.5/10. Published 2026-09-25.
- How severe is CVE-2026-66078?
- Medium severity. CVSS v3 base score is 5.5 out of 10.