CVE-2026-54904

HIGHNVD 7.57.5—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 7.5 under NVD CVSS v3. EPSS exploit probability: 0.4%, top 65% 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
Elevated
7.5EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 7.5Exploit: Elevated riskExposed: 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)
EG Risk
50(Track)
EG Risk 50/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity75% × 45%
Exploitation40% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
35%
KEV
Not listed

Published

June 19, 2026

Last Modified

August 5, 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

(5 across 5 ecosystems)
Debian:11(1)
PackageVulnerable rangeFixed inDependents
ruby-concurrent1.1.6+dfsg-3 ... 1.3.8-1 (16 versions)——
Debian:12(1)
PackageVulnerable rangeFixed inDependents
ruby-concurrent1.1.6+dfsg-5 ... 1.3.8-1 (14 versions)——
Debian:13(1)
PackageVulnerable rangeFixed inDependents
ruby-concurrent1.3.5-1 ... 1.3.8-1 (7 versions)——
Debian:14(1)
PackageVulnerable rangeFixed inDependents
ruby-concurrent1.3.5-1, 1.3.6-11.3.7-1—
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 12× in last 7d / 52× 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. 2026-08-23 00:19 UTCEPSS rescore
  2. 2026-08-22 23:37 UTCEG score recompute
  3. 2026-08-21 23:49 UTCEPSS rescore
  4. 2026-08-21 09:39 UTCEG score recompute
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  1. 2026-08-08 23:31 UTCEG score recompute
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  3. 2026-08-07 21:52 UTCEG score recompute
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  5. 2026-08-06 13:47 UTCEPSS rescore
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  7. 2026-08-05 19:17 UTCEPSS rescore
  8. 2026-08-05 18:32 UTCEG score recompute
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  11. 2026-08-04 15:10 UTCEPSS rescore
  12. 2026-08-04 10:39 UTCEPSS rescore
  13. 2026-08-02 06:41 UTCEG score recompute
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  17. 2026-07-30 22:18 UTCEG score recompute
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  22. 2026-07-28 15:37 UTCEPSS rescore
  23. 2026-07-27 21:19 UTCEG score recompute
  24. 2026-07-26 16:47 UTCEG score recompute
  25. 2026-07-26 14:54 UTCEPSS rescore
  26. 2026-07-25 14:18 UTCEPSS rescore
  27. 2026-07-24 14:18 UTCEPSS rescore
  28. 2026-07-23 14:18 UTCEPSS rescore
  29. 2026-07-23 03:20 UTCEG score recompute
  30. 2026-07-22 14:08 UTCEPSS rescore
  31. 2026-07-21 15:25 UTCEPSS rescore
  32. 2026-07-20 17:08 UTCEPSS rescore
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  48. 2026-07-09 19:10 UTCEPSS rescore
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  67. 2026-06-27 03:08 UTCEPSS rescore
  68. 2026-06-27 00:04 UTCEG score recompute▼ 0.70
  69. 2026-06-26 19:41 UTCNVD updateCVSS v3 → 7.5
  70. 2026-06-25 13:49 UTCEPSS rescore
  71. 2026-06-24 18:32 UTCEG score recompute▲ 8.20
  72. 2026-06-24 18:03 UTCNVD updateCVSS v3 → 8.2 · CVSS v4 → 8.2
  73. 2026-06-19 21:24 UTCEG score recompute

Related CVEs(same CWE)

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 August 5, 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 0% probability of exploitation in the next 30 days, which ranks it in the top 65.3% of all scored CVEs.
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.

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