{"id":"CVE-2026-66071","summary":"RabbitMQ: Atom exhaustion: OAuth2 JWT tag: scope values","details":"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.","aliases":["GHSA-89p2-f5cv-x5cg"],"modified":"2026-09-26T03:45:25.627706276Z","published":"2026-09-25T16:11:07.278Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/66xxx/CVE-2026-66071.json","unresolved_ranges":[{"extracted_events":[{"introduced":"3.13.0"},{"fixed":"3.13.15"},{"introduced":"4.0.0"},{"fixed":"4.0.22"},{"introduced":"4.1.0"},{"fixed":"4.1.11"}],"source":"AFFECTED_FIELD"}],"cna_assigner":"GitHub_M","cwe_ids":["CWE-400"]},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/66xxx/CVE-2026-66071.json"},{"type":"FIX","url":"https://github.com/rabbitmq/rabbitmq-server/commit/9a44124d9c932d6fc7d2a3b945e5a143e547bcb6"},{"type":"FIX","url":"https://github.com/rabbitmq/rabbitmq-server/commit/c5690583a53789a3bf00cca508b43e8246db0d11"},{"type":"WEB","url":"https://github.com/rabbitmq/rabbitmq-server/releases/tag/v4.2.6"},{"type":"WEB","url":"https://github.com/rabbitmq/rabbitmq-server/releases/tag/v4.3.1"},{"type":"ADVISORY","url":"https://github.com/rabbitmq/rabbitmq-server/security/advisories/GHSA-89p2-f5cv-x5cg"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-66071"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/rabbitmq/rabbitmq-server","events":[{"introduced":"95c501fbad76c66156346cf364d158d6e30aa4d9"},{"fixed":"8a56c37f099a7bf609a555de3f0ff8ed23964d20"},{"introduced":"1929eeadf9b2bac12c5434fb56884ef27370580e"},{"fixed":"49decca35e59d2cb774e5abd76412cee721308a5"}],"database_specific":{"extracted_events":[{"introduced":"4.2.0"},{"fixed":"4.2.6"},{"introduced":"4.3.0"},{"fixed":"4.3.1"}],"source":"AFFECTED_FIELD"}}],"versions":["v4.3.0","v4.2.5","v4.2.4","v4.2.3","v4.2.2","v4.2.1","v4.2.0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-66071.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V4","score":"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"}]}