ruby-concurrency concurrent-ruby up to 1.3.6 Float::NAN infinite loop

Summaryinfo

A vulnerability described as problematic has been identified in ruby-concurrency concurrent-ruby up to 1.3.6. This impacts the function Float::NAN. Executing a manipulation can lead to infinite loop. The identification of this vulnerability is CVE-2026-54904. The attack may be launched remotely. There is no exploit available. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability classified as problematic was found in ruby-concurrency concurrent-ruby up to 1.3.6. This vulnerability affects the function Float::NAN. The manipulation with an unknown input leads to a infinite loop vulnerability. The CWE definition for the vulnerability is CWE-835. The product contains an iteration or loop with an exit condition that cannot be reached, i.e., an infinite loop. As an impact it is known to affect availability. CVE summarizes:

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.

The advisory is available at github.com. This vulnerability was named CVE-2026-54904 since 06/16/2026. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. Technical details are known, but there is no available exploit. This vulnerability is assigned to T1499 by the MITRE ATT&CK project.

Upgrading to version 1.3.7 eliminates this vulnerability.

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Productinfo

Type

• Programming Language Software

Vendor

• ruby-concurrency

Name

• concurrent-ruby

Version

• 1.3.0
• 1.3.1
• 1.3.2
• 1.3.3
• 1.3.4
• 1.3.5
• 1.3.6

Website

• Product: https://github.com/ruby-concurrency/concurrent-ruby/

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