{"cve":"CVE-2026-66071","nvd":{"published":"2026-09-25T17:17:09.987","modified":"2026-10-15T20:14:57.567","status":"Analyzed","description":"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.","cvss_v4":{"vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N","score":6.0},"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","score":6.5},"cwes":["CWE-400"],"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":["broadcom:rabbitmq_server"],"source":"nvd","synced_at":"2026-10-19T22:56:02.509636177+00:00"},"epss":{"cve":"CVE-2026-66071","score":0.00542,"percentile":0.45303,"date":"2026-10-25"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}