{"id":"CVE-2026-66071","url":"https://www.cyber-defence.io/tools/cve/CVE-2026-66071","generatedAt":"2026-10-28T01:45:25.127Z","title":"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…","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.","published":"2026-09-25T17:17:10.000Z","lastModified":"2026-10-15T20:14:58.000Z","status":"Analyzed","sourceIdentifier":"security-advisories@github.com","cvss":{"version":"4.0","score":6,"severity":"MEDIUM","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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/M"},"cwe":["CWE-400"],"affected":["broadcom/rabbitmq server"],"epss":{"score":0.00542,"percentile":0.4532,"date":"2026-10-26","history":[{"date":"2026-09-26","score":0.00342,"percentile":0.2511}]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"low","text":"Lower severity and a low EPSS score (0.54%). Track it; it rarely justifies an emergency change on its own."},"changes":[{"kind":"new","label":"New CVE","at":"2026-09-25T17:17:10.000Z","detail":{"score":"6.0","severity":"MEDIUM","publishedAt":"2026-09-25T17:17:09.987Z"},"summary":"New CVE, medium severity (CVSS 6.0)."}],"references":[{"url":"https://github.com/rabbitmq/rabbitmq-server/commit/9a44124d9c932d6fc7d2a3b945e5a143e547bcb6","tags":["Patch"],"source":"security-advisories@github.com"},{"url":"https://github.com/rabbitmq/rabbitmq-server/commit/c5690583a53789a3bf00cca508b43e8246db0d11","tags":["Patch"],"source":"security-advisories@github.com"},{"url":"https://github.com/rabbitmq/rabbitmq-server/releases/tag/v4.2.6","tags":["Release Notes"],"source":"security-advisories@github.com"},{"url":"https://github.com/rabbitmq/rabbitmq-server/releases/tag/v4.3.1","tags":["Release Notes"],"source":"security-advisories@github.com"},{"url":"https://github.com/rabbitmq/rabbitmq-server/security/advisories/GHSA-89p2-f5cv-x5cg","tags":["Exploit","Third Party Advisory"],"source":"security-advisories@github.com"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-66071","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}