{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "extracted_events": [
              {
                "introduced": "4.2.0"
              },
              {
                "fixed": "4.2.6"
              },
              {
                "introduced": "4.3.0"
              },
              {
                "fixed": "4.3.1"
              }
            ],
            "source": [
              "AFFECTED_FIELD",
              "REFERENCES"
            ]
          },
          "events": [
            {
              "introduced": "95c501fbad76c66156346cf364d158d6e30aa4d9"
            },
            {
              "introduced": "1929eeadf9b2bac12c5434fb56884ef27370580e"
            },
            {
              "fixed": "8a56c37f099a7bf609a555de3f0ff8ed23964d20"
            },
            {
              "fixed": "49decca35e59d2cb774e5abd76412cee721308a5"
            },
            {
              "fixed": "9a44124d9c932d6fc7d2a3b945e5a143e547bcb6"
            },
            {
              "fixed": "c5690583a53789a3bf00cca508b43e8246db0d11"
            }
          ],
          "repo": "https://github.com/rabbitmq/rabbitmq-server",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-89p2-f5cv-x5cg"
  ],
  "database_specific": {
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
      "CWE-400"
    ],
    "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"
      }
    ]
  },
  "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.",
  "id": "CVE-2026-66071",
  "modified": "2026-09-27T03:30:34.833463553Z",
  "published": "2026-09-25T16:11:07.278Z",
  "references": [
    {
      "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/CVEProject/cvelistV5/tree/main/cves/2026/66xxx/CVE-2026-66071.json"
    },
    {
      "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"
    },
    {
      "type": "FIX",
      "url": "https://github.com/rabbitmq/rabbitmq-server/commit/9a44124d9c932d6fc7d2a3b945e5a143e547bcb6"
    },
    {
      "type": "FIX",
      "url": "https://github.com/rabbitmq/rabbitmq-server/commit/c5690583a53789a3bf00cca508b43e8246db0d11"
    }
  ],
  "schema_version": "1.9.0",
  "severity": [
    {
      "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",
      "type": "CVSS_V4"
    }
  ],
  "summary": "RabbitMQ: Atom exhaustion: OAuth2 JWT tag: scope values"
}