{"id":"DEBIAN-CVE-2026-54904","details":"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.","modified":"2026-09-01T16:06:51.754011164Z","published":"2026-06-24T17:17:29.267Z","upstream":["CVE-2026-54904"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2026-54904"}],"affected":[{"package":{"name":"ruby-concurrent","ecosystem":"Debian:12","purl":"pkg:deb/debian/ruby-concurrent?arch=source&distro=bookworm"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.1.6+dfsg-5","1.2.3-1","1.2.3-2","1.2.3-3","1.2.3-4","1.3.4-1","1.3.4-1~exp1","1.3.5-1","1.3.6-1","1.3.7-1","1.3.7-2","1.3.7-3","1.3.7-4","1.3.8-1"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2026-54904.json"}},{"package":{"name":"ruby-concurrent","ecosystem":"Debian:13","purl":"pkg:deb/debian/ruby-concurrent?arch=source&distro=trixie"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.3.5-1","1.3.6-1","1.3.7-1","1.3.7-2","1.3.7-3","1.3.7-4","1.3.8-1"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2026-54904.json"}},{"package":{"name":"ruby-concurrent","ecosystem":"Debian:14","purl":"pkg:deb/debian/ruby-concurrent?arch=source&distro=forky"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.3.7-1"}]}],"versions":["1.3.5-1","1.3.6-1"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2026-54904.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"}]}