CVE-2026-54904

HIGHNVD 7.57.5—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 7.5 under NVD CVSS v3. EPSS exploit probability: 0.3%, top 80% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, nvd
7.5
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 0%CVSS: 7.5Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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.

CVSS v3
7.5
EG Score
7.5(medium)
EPSS
19.6%
KEV
Not listed

Published

June 19, 2026

Last Modified

June 26, 2026

Advisory Details (1)

Auto-updated Jun 24, 2026
🔬 Proof of concept available. Patch available. Sources: github.
github Patch Available🟡 PoC Available

`AtomicReference#update` livelocks when the stored value is `Float::NAN` · Advisory · ruby-concurrency/concurrent-ruby · GitHub

https://github.com/ruby-concurrency/concurrent-ruby/security/advisories/GHSA-h8w8-99g7-qmvj

Vendor Advisories for CVE-2026-54904(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Affected Packages

(1 across 1 ecosystem)
RubyGems(1)
PackageVulnerable rangeFixed inDependents
concurrent-ruby0.0.1 ... 1.3.6 (77 versions)1.3.7—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 23× in last 7d / 44× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-07-07 04:43 UTCEG score recompute
  2. 2026-07-06 16:27 UTCEPSS rescore
  3. 2026-07-06 16:27 UTCEPSS rescore
  4. 2026-07-06 15:49 UTCEG score recompute
  5. 2026-07-06 02:58 UTCEG score recompute
  6. 2026-07-06 02:23 UTCEPSS rescore
  7. 2026-07-06 02:23 UTCEPSS rescore
  8. 2026-07-05 14:09 UTCEG score recompute
  9. 2026-07-05 02:31 UTCEPSS rescore
  10. 2026-07-05 02:30 UTCEPSS rescore
  11. 2026-07-05 01:17 UTCEG score recompute
  12. 2026-07-04 12:10 UTCEG score recompute
  13. 2026-07-04 06:31 UTCEPSS rescore
  14. 2026-07-04 06:31 UTCEPSS rescore
  15. 2026-07-03 23:15 UTCEG score recompute
  16. 2026-07-03 10:13 UTCEG score recompute
  17. 2026-07-02 21:22 UTCEG score recompute
  18. 2026-07-02 08:32 UTCEG score recompute
  19. 2026-07-01 19:41 UTCEG score recompute
  20. 2026-07-01 15:07 UTCEPSS rescore
  21. 2026-07-01 06:51 UTCEG score recompute
  22. 2026-06-30 23:22 UTCEPSS rescore
  23. 2026-06-30 18:00 UTCEG score recompute
  24. 2026-06-30 05:10 UTCEG score recompute
  25. 2026-06-29 16:16 UTCEG score recompute
Show 19 more
  1. 2026-06-29 14:06 UTCEPSS rescore
  2. 2026-06-29 14:06 UTCEPSS rescore
  3. 2026-06-29 03:24 UTCEG score recompute
  4. 2026-06-28 14:34 UTCEG score recompute
  5. 2026-06-28 14:07 UTCEPSS rescore
  6. 2026-06-28 04:56 UTCEPSS rescore
  7. 2026-06-28 04:56 UTCEPSS rescore
  8. 2026-06-28 01:44 UTCEG score recompute
  9. 2026-06-27 12:54 UTCEG score recompute
  10. 2026-06-27 03:08 UTCEPSS rescore
  11. 2026-06-27 00:04 UTCEG score recompute▼ 0.70
  12. 2026-06-26 19:41 UTCNVD updateCVSS v3 → 7.5
  13. 2026-06-26 11:13 UTCEG score recompute
  14. 2026-06-25 20:16 UTCEG score recompute
  15. 2026-06-25 13:49 UTCEPSS rescore
  16. 2026-06-25 07:24 UTCEG score recompute
  17. 2026-06-24 18:32 UTCEG score recompute▲ 8.20
  18. 2026-06-24 18:03 UTCNVD updateCVSS v3 → 8.2 · CVSS v4 → 8.2
  19. 2026-06-19 21:24 UTCEG score recompute

Frequently asked(5)

What is CVE-2026-54904?
CVE-2026-54904 is a high vulnerability published on June 19, 2026. 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 compareandset(oldvalue,…
When was CVE-2026-54904 disclosed?
CVE-2026-54904 was first published in the National Vulnerability Database on June 19, 2026, with the most recent update on June 26, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-54904 actively exploited?
CVE-2026-54904 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 19.6% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-54904?
CVE-2026-54904 has a CVSS v3 base score of 7.5 (NVD).
How do I remediate CVE-2026-54904?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-54904, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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