Concurrency Tools for Ruby Vulnerability in Concurrent Ruby by Ruby Concurrency
CVE-2026-54904

8.2HIGH

Key Information:

Vendor

Ruby-concurrency

Status
Concurrent-ruby
Vendor
CVE Published:
24 June 2026

What is CVE-2026-54904?

The Concurrent Ruby library, a set of modern concurrency tools for Ruby, contains a logic flaw in versions prior to 1.3.7. When the value in an AtomicReference is set to Float::NAN, calls to the update method can enter an infinite loop, leading to CPU exhaustion and preventing the application from processing further requests. This occurs due to the failure of Numeric's compare_and_set to recognize Float::NAN as equal to itself. As a result, services utilizing AtomicReference with non-standard numeric values may experience severe performance degradation or total service lock-up. Users are encouraged to upgrade to version 1.3.7 to mitigate this issue.

Affected Version(s)

concurrent-ruby < 1.3.7

References

https://github.com/ruby-concurrency/concurrent-ruby/secur...
x_refsource_CONFIRM
https://github.com/ruby-concurrency/concurrent-ruby/commi...
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https://github.com/ruby-concurrency/concurrent-ruby/relea...
x_refsource_MISC

CVSS V4

Score:
8.2
Severity:
HIGH
Confidentiality:
None
Integrity:
None
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Attack Required:
Physical
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • Vulnerability published

  • Vulnerability Reserved

.