RabbitMQ: Atom exhaustion: OAuth2 JWT tag: scope values

{
  "id": "53c24b6371b730e602824047c16032e69cf573d571e3aa776ce5811e9b18858e",
  "url": "https://osv.dev/vulnerability/BIT-rabbitmq-2026-66071",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "RabbitMQ: Atom exhaustion: OAuth2 JWT tag: scope values",
    "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 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.",
    "evidence": "osv:BIT-rabbitmq-2026-66071",
    "products": [
      {
        "name": {
          "value": "rabbitmq",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "3.13.15",
            "evidence": "/affected/0/ranges"
          },
          {
            "value": "4.0.22",
            "evidence": "/affected/0/ranges"
          },
          {
            "value": "4.1.11",
            "evidence": "/affected/0/ranges"
          },
          {
            "value": "4.2.6",
            "evidence": "/affected/0/ranges"
          },
          {
            "value": "4.3.1",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "medium",
    "structured": {
      "id": "BIT-rabbitmq-2026-66071",
      "aliases": [
        "BIT-rabbitmq-2026-66071",
        "CVE-2026-66071",
        "GHSA-89p2-f5cv-x5cg"
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "SEMVER",
              "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"
                },
                {
                  "introduced": "4.2.0"
                },
                {
                  "fixed": "4.2.6"
                },
                {
                  "introduced": "4.3.0"
                },
                {
                  "fixed": "4.3.1"
                }
              ]
            }
          ],
          "package": {
            "name": "rabbitmq",
            "purl": "pkg:bitnami/rabbitmq",
            "ecosystem": "Bitnami"
          },
          "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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X"
            }
          ],
          "database_specific": {
            "source": "https://github.com/bitnami/vulndb/tree/main/data/rabbitmq/BIT-rabbitmq-2026-66071.json"
          }
        }
      ],
      "modified": "2026-10-16T09:45:20.661039775Z",
      "provider": "osv",
      "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",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-66071"
      ],
      "provider_metadata": {
        "cpes": [
          "cpe:2.3:a:vmware:rabbitmq:*:*:*:*:*:*:*:*"
        ],
        "severity": "Medium"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-66071",
        "evidence": "/aliases"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/database_specific/severity"
  },
  "source_id": "core-osv",
  "document_id": 338390,
  "published_at": "2026-10-01T09:32:47.099+00:00"
}