{"id":"CVE-2026-66071","title":"RabbitMQ is a messaging and streaming broker","summary":"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 rabbitdatacoercio…","severity":"medium","cvss":6.5,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","cwe":["CWE-400","CWE-770"],"vendor":"broadcom","product":"rabbitmq_server","affected":["rabbitmq_server >= 3.13.0, < 3.13.15","rabbitmq_server >= 4.0.0, < 4.0.22","rabbitmq_server >= 4.1.0, < 4.1.11","rabbitmq_server >= 4.2.0, < 4.2.6","rabbitmq_server >= 4.3.0, < 4.3.1"],"patched":["rabbitmq_server 4.3.1"],"published":"2026-09-25","updated":"2026-10-15","sourceUpdated":"2026-10-15T20:14:57.567","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-66071","references":[{"url":"https://github.com/rabbitmq/rabbitmq-server/commit/9a44124d9c932d6fc7d2a3b945e5a143e547bcb6","label":"security-advisories@github.com"},{"url":"https://github.com/rabbitmq/rabbitmq-server/commit/c5690583a53789a3bf00cca508b43e8246db0d11","label":"security-advisories@github.com"},{"url":"https://github.com/rabbitmq/rabbitmq-server/releases/tag/v4.2.6","label":"security-advisories@github.com"},{"url":"https://github.com/rabbitmq/rabbitmq-server/releases/tag/v4.3.1","label":"security-advisories@github.com"},{"url":"https://github.com/rabbitmq/rabbitmq-server/security/advisories/GHSA-89p2-f5cv-x5cg","label":"security-advisories@github.com"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-66071.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-66071"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2541515"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-66071"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-66071"},{"url":"https://access.redhat.com/errata/RHSA-2026:67552"}],"tags":["nvd","cve.org","csaf","vex","red-hat"],"epss":0.00542,"epssPercentile":0.45388,"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"partial","timestamp":"2026-09-25T17:53:05.694643Z"},"scores":{"nvd":6.5,"cna":6,"vendor":5.3},"ingestedAt":"2026-09-25T17:13:14.028Z","slug":"CVE-2026-66071","body":"## Overview\n\nRabbitMQ 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.\n\n## Affected\n\n- `rabbitmq_server >= 3.13.0, < 3.13.15`\n- `rabbitmq_server >= 4.0.0, < 4.0.22`\n- `rabbitmq_server >= 4.1.0, < 4.1.11`\n- `rabbitmq_server >= 4.2.0, < 4.2.6`\n- `rabbitmq_server >= 4.3.0, < 4.3.1`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `rabbitmq_server 4.3.1`\n\n## Vendor advisories\n\n- **RHSA-2026:67552** · Red Hat · fixed in: Red Hat Hardened Images · released 2026-09-15 · [advisory](https://access.redhat.com/errata/RHSA-2026:67552)\n- **Red Hat VEX** · Moderate · affected: Red Hat Hardened Images, Red Hat OpenStack Platform 13 (Queens), Red Hat OpenStack Platform 16.2, Red Hat OpenStack Platform 17.1, Red Hat OpenStack Platform 18.0 · no fix planned: Red Hat OpenStack Platform 13 (Queens), Red Hat OpenStack Platform 16.2, Red Hat OpenStack Platform 17.1, Red Hat Hardened Images, … · updated 2026-10-03 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-66071.json)","depth":"sunlit","depthScore":36,"depthScoreParts":{"impact":35.8,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[{"seq":230116,"id":"CVE-2026-66071","ts":1793124792549,"field":"cvss","old":"6","new":"6.5"}]}