{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-54904","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","state":"PUBLISHED","assignerShortName":"GitHub_M","dateReserved":"2026-06-16T13:49:33.556Z","datePublished":"2026-06-24T15:44:21.992Z","dateUpdated":"2026-08-05T17:36:28.452Z"},"containers":{"cna":{"title":"concurrent-ruby:  `AtomicReference#update` livelocks when the stored value is `Float::NAN`","problemTypes":[{"descriptions":[{"cweId":"CWE-835","lang":"en","description":"CWE-835: Loop with Unreachable Exit Condition ('Infinite Loop')","type":"CWE"}]}],"metrics":[{"cvssV4_0":{"attackVector":"NETWORK","attackComplexity":"LOW","attackRequirements":"PRESENT","privilegesRequired":"NONE","userInteraction":"NONE","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"NONE","vulnAvailabilityImpact":"HIGH","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","subAvailabilityImpact":"NONE","baseScore":8.2,"baseSeverity":"HIGH","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","version":"4.0"}}],"references":[{"name":"https://github.com/ruby-concurrency/concurrent-ruby/security/advisories/GHSA-h8w8-99g7-qmvj","tags":["x_refsource_CONFIRM"],"url":"https://github.com/ruby-concurrency/concurrent-ruby/security/advisories/GHSA-h8w8-99g7-qmvj"},{"name":"https://github.com/ruby-concurrency/concurrent-ruby/commit/6e37e0644b83b182971dc540d2e4bee38df61386","tags":["x_refsource_MISC"],"url":"https://github.com/ruby-concurrency/concurrent-ruby/commit/6e37e0644b83b182971dc540d2e4bee38df61386"},{"name":"https://github.com/ruby-concurrency/concurrent-ruby/releases/tag/v1.3.7","tags":["x_refsource_MISC"],"url":"https://github.com/ruby-concurrency/concurrent-ruby/releases/tag/v1.3.7"},{"name":"https://github.com/rubysec/ruby-advisory-db/blob/master/gems/concurrent-ruby/CVE-2026-54904.yml","tags":["x_refsource_MISC"],"url":"https://github.com/rubysec/ruby-advisory-db/blob/master/gems/concurrent-ruby/CVE-2026-54904.yml"}],"affected":[{"vendor":"ruby-concurrency","product":"concurrent-ruby","versions":[{"version":"< 1.3.7","status":"affected"}]}],"providerMetadata":{"orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","shortName":"GitHub_M","dateUpdated":"2026-08-05T17:36:28.452Z"},"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."}],"source":{"advisory":"GHSA-h8w8-99g7-qmvj","discovery":"UNKNOWN"}},"adp":[{"references":[{"url":"https://github.com/ruby-concurrency/concurrent-ruby/security/advisories/GHSA-h8w8-99g7-qmvj","tags":["exploit"]}],"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-06-25T13:19:55.812897Z","id":"CVE-2026-54904","options":[{"Exploitation":"poc"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"title":"CISA ADP Vulnrichment","providerMetadata":{"orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP","dateUpdated":"2026-06-25T13:20:00.135Z"}}]}}