cve-2026-54904

{
  "cvss": 8.2,
  "datePublished": "2026-06-24T17:17:29.267",
  "dateUpdated": "2026-10-25T22:10:00.150",
  "description": "concurrent-ruby is a modern concurrency tools for Ruby. Prior to 1.3.7, Concurrent::AtomicReference#update can enter a permanent busy retry loop when the current value is Float::NAN. The issue is caused by the interaction between AtomicReference#update, which retries until compare_and_set(old_value, new_value) succeeds; Numeric compare_and_set, which checks old == old_value before attempting the underlying atomic swap.; and Ruby NaN semantics, where Float::NAN == Float::NAN is always false. As a result, once an AtomicReference contains Float::NAN, calling #update repeatedly evaluates the caller's block and never returns. In services that store externally derived numeric values in an AtomicReference, this can cause CPU exhaustion or permanent request/job hangs. This vulnerability is fixed in 1.3.7.",
  "id": "CVE-2026-54904",
  "raw": {
    "affected": [
      {
        "affectedData": [
          {
            "product": "concurrent-ruby",
            "vendor": "ruby-concurrency",
            "versions": [
              {
                "status": "affected",
                "version": "< 1.3.7"
              }
            ]
          }
        ],
        "source": "security-advisories@github.com"
      }
    ],
    "configurations": [
      {
        "nodes": [
          {
            "cpeMatch": [
              {
                "criteria": "cpe:2.3:a:rubyconcurrency:concurrent_ruby:*:*:*:*:*:ruby:*:*",
                "matchCriteriaId": "4BBFFB42-BEF4-4DF8-BAB8-4B728A8CA930",
                "versionEndExcluding": "1.3.7",
                "vulnerable": true
              }
            ],
            "negate": false,
            "operator": "OR"
          }
        ]
      }
    ],
    "cveTags": [],
    "descriptions": [
      {
        "lang": "en",
        "value": "concurrent-ruby is a modern concurrency tools for Ruby. Prior to 1.3.7, Concurrent::AtomicReference#update can enter a permanent busy retry loop when the current value is Float::NAN. The issue is caused by the interaction between AtomicReference#update, which retries until compare_and_set(old_value, new_value) succeeds; Numeric compare_and_set, which checks old == old_value before attempting the underlying atomic swap.; and Ruby NaN semantics, where Float::NAN == Float::NAN is always false. As a result, once an AtomicReference contains Float::NAN, calling #update repeatedly evaluates the caller's block and never returns. In services that store externally derived numeric values in an AtomicReference, this can cause CPU exhaustion or permanent request/job hangs. This vulnerability is fixed in 1.3.7."
      },
      {
        "lang": "es",
        "value": "concurrent-ruby es un conjunto de herramientas modernas de concurrencia para Ruby. Antes de la versión 1.3.7, Concurrent::AtomicReference#update puede entrar en un bucle de reintento ocupado permanente cuando el valor actual es Float::NAN. El problema es causado por la interacción entre AtomicReference#update, que reintenta hasta que compare_and_set(old_value, new_value) tiene éxito; Numeric compare_and_set, que comprueba old == old_value antes de intentar el intercambio atómico subyacente; y la semántica NaN de Ruby, donde Float::NAN == Float::NAN es siempre falso. Como resultado, una vez que un AtomicReference contiene Float::NAN, llamar a #update repetidamente evalúa el bloque del llamador y nunca regresa. En servicios que almacenan valores numéricos derivados externamente en un AtomicReference, esto puede causar agotamiento de la CPU o bloqueos permanentes de solicitudes/tareas. Esta vulnerabilidad está corregida en la versión 1.3.7."
      }
    ],
    "id": "CVE-2026-54904",
    "lastModified": "2026-10-25T22:10:00.150",
    "metrics": {
      "cvssMetricV31": [
        {
          "cvssData": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "HIGH",
            "baseScore": 7.5,
            "baseSeverity": "HIGH",
            "confidentialityImpact": "NONE",
            "integrityImpact": "NONE",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
            "version": "3.1"
          },
          "exploitabilityScore": 3.9,
          "impactScore": 3.6,
          "source": "nvd@nist.gov",
          "type": "Primary"
        }
      ],
      "cvssMetricV40": [
        {
          "cvssData": {
            "Automatable": "NOT_DEFINED",
            "Recovery": "NOT_DEFINED",
            "Safety": "NOT_DEFINED",
            "attackComplexity": "LOW",
            "attackRequirements": "PRESENT",
            "attackVector": "NETWORK",
            "availabilityRequirement": "NOT_DEFINED",
            "baseScore": 8.2,
            "baseSeverity": "HIGH",
            "confidentialityRequirement": "NOT_DEFINED",
            "exploitMaturity": "NOT_DEFINED",
            "integrityRequirement": "NOT_DEFINED",
            "modifiedAttackComplexity": "NOT_DEFINED",
            "modifiedAttackRequirements": "NOT_DEFINED",
            "modifiedAttackVector": "NOT_DEFINED",
            "modifiedPrivilegesRequired": "NOT_DEFINED",
            "modifiedSubAvailabilityImpact": "NOT_DEFINED",
            "modifiedSubConfidentialityImpact": "NOT_DEFINED",
            "modifiedSubIntegrityImpact": "NOT_DEFINED",
            "modifiedUserInteraction": "NOT_DEFINED",
            "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
            "modifiedVulnConfidentialityImpact": "NOT_DEFINED",
            "modifiedVulnIntegrityImpact": "NOT_DEFINED",
            "privilegesRequired": "NONE",
            "providerUrgency": "NOT_DEFINED",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "NONE",
            "valueDensity": "NOT_DEFINED",
            "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/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",
            "version": "4.0",
            "vulnAvailabilityImpact": "HIGH",
            "vulnConfidentialityImpact": "NONE",
            "vulnIntegrityImpact": "NONE",
            "vulnerabilityResponseEffort": "NOT_DEFINED"
          },
          "source": "security-advisories@github.com",
          "type": "Secondary"
        }
      ],
      "ssvcV203": [
        {
          "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "ssvcData": {
            "id": "CVE-2026-54904",
            "options": [
              {
                "exploitation": "poc"
              },
              {
                "automatable": "no"
              },
              {
                "technicalImpact": "partial"
              }
            ],
            "role": "CISA Coordinator",
            "timestamp": "2026-06-25T13:19:55.812897Z",
            "version": "2.0.3"
          }
        }
      ]
    },
    "published": "2026-06-24T17:17:29.267",
    "references": [
      {
        "source": "security-advisories@github.com",
        "url": "https://github.com/ruby-concurrency/concurrent-ruby/commit/6e37e0644b83b182971dc540d2e4bee38df61386"
      },
      {
        "source": "security-advisories@github.com",
        "url": "https://github.com/ruby-concurrency/concurrent-ruby/releases/tag/v1.3.7"
      },
      {
        "source": "security-advisories@github.com",
        "tags": [
          "Exploit",
          "Third Party Advisory"
        ],
        "url": "https://github.com/ruby-concurrency/concurrent-ruby/security/advisories/GHSA-h8w8-99g7-qmvj"
      },
      {
        "source": "security-advisories@github.com",
        "url": "https://github.com/rubysec/ruby-advisory-db/blob/master/gems/concurrent-ruby/CVE-2026-54904.yml"
      },
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "tags": [
          "Exploit",
          "Third Party Advisory"
        ],
        "url": "https://github.com/ruby-concurrency/concurrent-ruby/security/advisories/GHSA-h8w8-99g7-qmvj"
      }
    ],
    "sourceIdentifier": "security-advisories@github.com",
    "vulnStatus": "Modified",
    "weaknesses": [
      {
        "description": [
          {
            "lang": "en",
            "value": "CWE-835"
          }
        ],
        "source": "security-advisories@github.com",
        "type": "Secondary"
      }
    ]
  },
  "severity": "HIGH",
  "source": "nvd",
  "title": "concurrent-ruby is a modern concurrency tools for Ruby"
}