{"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"}