CVE-2026-54904 concurrent-ruby: `AtomicReference#update` livelocks when the stored value is `Float::NAN`

concurrent-ruby is a modern concurrency tools for Ruby. Prior to 1.3.7, Concurrent::AtomicReferenceupdate can enter a permanent busy retry loop when the current value is Float::NAN. The issue is caused by the interaction between AtomicReferenceupdate, which retries until compareandsetoldvalue,...

Concurrent Ruby : `AtomicReference#update` livelocks when the stored value is `Float::NAN`

Summary Concurrent::AtomicReferenceupdate can enter a permanent busy retry loop when the current value is Float::NAN. The issue is caused by the interaction between: - AtomicReferenceupdate, which retries until compareandsetoldvalue, newvalue succeeds. - Numeric compareandset, which checks old ==...

PT-2026-51090

Name of the Vulnerable Software and Affected Versions concurrent-ruby versions prior to 1.3.7 Description The Concurrent::AtomicReferenceupdate function can enter a permanent busy retry loop when the current value is Float::NAN. This occurs due to the interaction between AtomicReferenceupdate,...