CVE-2026-54904

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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 versi\u00f3n 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 interacci\u00f3n entre AtomicReference#update, que reintenta hasta que compare_and_set(old_value, new_value) tiene \u00e9xito; Numeric compare_and_set, que comprueba old == old_value antes de intentar el intercambio at\u00f3mico subyacente; y la sem\u00e1ntica 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 eval\u00faa el bloque del llamador y nunca regresa. En servicios que almacenan valores num\u00e9ricos derivados externamente en un AtomicReference, esto puede causar agotamiento de la CPU o bloqueos permanentes de solicitudes/tareas. Esta vulnerabilidad est\u00e1 corregida en la versi\u00f3n 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"}]}

{"bugzilla": {"description": "concurrent-ruby: rubygem-concurrent-ruby: concurrent-ruby: Denial of Service due to infinite loop in AtomicReference#update", "id": "2492250", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2492250"}, "csaw": false, "cvss3": {"cvss3_base_score": "5.9", "cvss3_scoring_vector": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H", "status": "draft"}, "cwe": "CWE-835", "details": ["A flaw was found in concurrent-ruby. A remote attacker could exploit a vulnerability in the Concurrent::AtomicReference#update method, which can enter a permanent busy retry loop. This occurs when the current value is a special 'Not a Number' (Float::NAN) floating-point value, causing the method to repeatedly attempt an operation without success. This can lead to a Denial of Service (DoS), where the affected application experiences CPU exhaustion or becomes unresponsive."], "mitigation": {"lang": "en:us", "value": "The vulnerable `AtomicReference#update` code path is not exercised with externally-derived numeric values, making exploitation not possible in this context. \nUpdating to concurrent-ruby 1.3.7 when available in upstream dependencies will fully resolve this issue."}, "name": "CVE-2026-54904", "package_state": [{"cpe": "cpe:/a:redhat:red_hat_3scale_amp:2", "fix_state": "Not affected", "package_name": "3scale-amp21/backend", "product_name": "Red Hat 3scale API Management Platform 2"}, {"cpe": "cpe:/a:redhat:red_hat_3scale_amp:2", "fix_state": "Not affected", "package_name": "3scale-amp21/system", "product_name": "Red Hat 3scale API Management Platform 2"}, {"cpe": "cpe:/a:redhat:red_hat_3scale_amp:2", "fix_state": "Not affected", "package_name": "3scale-amp21/zync", "product_name": "Red Hat 3scale API Management Platform 2"}, {"cpe": "cpe:/a:redhat:red_hat_3scale_amp:2", "fix_state": "Not affected", "package_name": "3scale-amp22/backend", "product_name": "Red Hat 3scale API Management Platform 2"}, {"cpe": "cpe:/a:redhat:red_hat_3scale_amp:2", "fix_state": "Not affected", "package_name": "3scale-amp22/system", "product_name": "Red Hat 3scale API Management Platform 2"}, {"cpe": "cpe:/a:redhat:red_hat_3scale_amp:2", "fix_state": "Not affected", "package_name": "3scale-amp22/zync", "product_name": "Red Hat 3scale API Management Platform 2"}, {"cpe": "cpe:/a:redhat:red_hat_3scale_amp:2", "fix_state": "Not affected", "package_name": "3scale-amp26/toolbox", "product_name": "Red Hat 3scale API Management Platform 2"}, {"cpe": "cpe:/a:redhat:red_hat_3scale_amp:2", "fix_state": "Not affected", "package_name": "3scale-amp2/backend-rhel8", "product_name": "Red Hat 3scale API Management Platform 2"}, {"cpe": "cpe:/a:redhat:red_hat_3scale_amp:2", "fix_state": "Not affected", "package_name": "3scale-amp2/system-rhel7", "product_name": "Red Hat 3scale API Management Platform 2"}, {"cpe": "cpe:/a:redhat:red_hat_3scale_amp:2", "fix_state": "Not affected", "package_name": "3scale-amp2/system-rhel8", "product_name": "Red Hat 3scale API Management Platform 2"}, {"cpe": "cpe:/a:redhat:red_hat_3scale_amp:2", "fix_state": "Not affected", "package_name": "3scale-amp2/system-rhel9", "product_name": "Red Hat 3scale API Management Platform 2"}, {"cpe": "cpe:/a:redhat:red_hat_3scale_amp:2", "fix_state": "Not affected", "package_name": "3scale-amp2/toolbox-rhel8", "product_name": "Red Hat 3scale API Management Platform 2"}, {"cpe": "cpe:/a:redhat:red_hat_3scale_amp:2", "fix_state": "Not affected", "package_name": "3scale-amp2/toolbox-rhel9", "product_name": "Red Hat 3scale API Management Platform 2"}, {"cpe": "cpe:/a:redhat:red_hat_3scale_amp:2", "fix_state": "Not affected", "package_name": "3scale-amp2/zync-rhel8", "product_name": "Red Hat 3scale API Management Platform 2"}, {"cpe": "cpe:/a:redhat:red_hat_3scale_amp:2", "fix_state": "Not affected", "package_name": "3scale-amp2/zync-rhel9", "product_name": "Red Hat 3scale API Management Platform 2"}, {"cpe": "cpe:/a:redhat:openstack:17.1", "fix_state": "Not affected", "package_name": "rubygem-concurrent-ruby", "product_name": "Red Hat OpenStack Platform 17.1"}, {"cpe": "cpe:/a:redhat:satellite:6", "fix_state": "Not affected", "package_name": "rubygem-concurrent-ruby", "product_name": "Red Hat Satellite 6"}, {"cpe": "cpe:/a:redhat:satellite:6", "fix_state": "Not affected", "package_name": "satellite:el8/rubygem-concurrent-ruby", "product_name": "Red Hat Satellite 6"}], "public_date": "2026-06-24T15:44:21Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-54904\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-54904\nhttps://github.com/ruby-concurrency/concurrent-ruby/security/advisories/GHSA-h8w8-99g7-qmvj"], "statement": "The issue arises when the `AtomicReference#update` method encounters a `Float::NAN` value, leading to an infinite retry loop and potential CPU exhaustion. The vulnerable `AtomicReference#update` method is not used with externally-controlled (e.g: `Float::NAN`) values - thus exploitation is not possible.", "threat_severity": "Moderate"}

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