CVE-2013-4366

CRITICALNVD 9.89.8—
EchelonGraph scoreMEDIUM confidence

This critical-severity CVE scores 9.8 under NVD CVSS v3. EPSS exploit probability: 2.2%, top 20% 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
9.8
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 2%CVSS: 9.8Exploit: NoneExposed: 0

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

http/impl/client/HttpClientBuilder.java in Apache HttpClient 4.3.x before 4.3.1 does not ensure that X509HostnameVerifier is not null, which allows attackers to have unspecified impact via vectors involving hostname verification.

CVSS v3
9.8
EG Score
9.8(medium)
EG Risk
49(Track)
EG Risk 49/100SSVC: 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
Severity98% × 45%
Exploitation2% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS
80.5%
KEV
Not listed

Published

October 30, 2017

Last Modified

May 13, 2026

Advisory Details (1)

Auto-updated May 17, 2026
No patch confirmed yet.
generic
http://www.apache.org/dist/httpcomponents/httpclient/RELEASE_NOTES-4.3.x.txt

Affected Packages

(1 across 1 ecosystem)
Maven(1)
PackageVulnerable rangeFixed inDependents
org.apache.httpcomponents:httpclient4.34.3.1—

Data Freshness Timeline

(refreshed 14× in last 7d / 38× 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. 2026-07-23 01:10 UTCEG score recompute
  2. 2026-07-23 00:14 UTCEG score recompute
  3. 2026-07-22 21:52 UTCEG score recompute
  4. 2026-07-22 14:04 UTCEPSS rescore
  5. 2026-07-22 14:04 UTCEPSS rescore
  6. 2026-07-21 15:21 UTCEPSS rescore
  7. 2026-07-20 17:03 UTCEPSS rescore
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  9. 2026-07-19 14:27 UTCEPSS rescore
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  14. 2026-07-16 16:58 UTCEPSS rescore
  15. 2026-07-15 16:54 UTCEPSS rescore
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  18. 2026-07-13 22:26 UTCEPSS rescore
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  20. 2026-07-11 08:23 UTCEPSS rescore
  21. 2026-07-09 19:05 UTCEPSS rescore
  22. 2026-07-08 15:10 UTCEPSS rescore
  23. 2026-07-08 08:57 UTCOSV refresh
  24. 2026-07-06 02:19 UTCEPSS rescore
  25. 2026-07-06 02:19 UTCEPSS rescore
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  1. 2026-07-05 02:26 UTCEPSS rescore
  2. 2026-07-04 06:27 UTCEPSS rescore
  3. 2026-07-01 15:02 UTCEPSS rescore
  4. 2026-06-30 23:19 UTCEPSS rescore
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  6. 2026-06-28 14:03 UTCEPSS rescore
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  9. 2026-06-27 03:05 UTCEPSS rescore
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  13. 2026-06-23 21:30 UTCEPSS rescore
  14. 2026-06-21 14:53 UTCEPSS rescore
  15. 2026-06-19 20:36 UTCOSV refresh
  16. 2026-06-19 19:23 UTCEPSS rescore
  17. 2026-06-19 19:22 UTCEPSS rescore
  18. 2026-06-18 17:49 UTCEPSS rescore
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  20. 2026-06-17 17:49 UTCEPSS rescore
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  22. 2026-06-16 17:49 UTCEPSS rescore
  23. 2026-06-16 17:49 UTCEPSS rescore
  24. 2026-06-15 17:44 UTCEPSS rescore
  25. 2026-06-14 23:14 UTCEPSS rescore
  26. 2026-06-13 22:57 UTCEPSS rescore
  27. 2026-06-12 23:08 UTCEPSS rescore
  28. 2026-06-11 13:56 UTCEPSS rescore
  29. 2026-06-10 13:18 UTCEPSS rescore
  30. 2026-06-08 14:14 UTCEPSS rescore
  31. 2026-06-07 15:22 UTCEPSS rescore
  32. 2026-06-06 13:45 UTCEPSS rescore
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  38. 2026-06-02 20:10 UTCEPSS rescore
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  40. 2026-06-01 13:49 UTCEPSS rescore
  41. 2026-06-01 13:49 UTCEPSS rescore
  42. 2026-05-31 22:28 UTCEPSS rescore
  43. 2026-05-31 22:28 UTCEPSS rescore
  44. 2026-05-31 00:50 UTCOSV refresh
  45. 2026-05-31 00:14 UTCEPSS rescore
  46. 2026-05-31 00:14 UTCEPSS rescore
  47. 2026-05-29 13:41 UTCEPSS rescore
  48. 2026-05-29 13:41 UTCEPSS rescore
  49. 2026-05-28 13:42 UTCEPSS rescore
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  52. 2026-05-27 13:38 UTCEPSS rescore
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  54. 2026-05-26 13:41 UTCEPSS rescore
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  56. 2026-05-26 07:16 UTCEPSS rescore
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  59. 2026-05-22 21:15 UTCEPSS rescore
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  68. 2026-05-18 23:11 UTCEG score recompute
  69. 2026-05-18 21:29 UTCEPSS rescore
  70. 2026-05-18 21:29 UTCEPSS rescore

Frequently asked(5)

What is CVE-2013-4366?
CVE-2013-4366 is a critical vulnerability published on October 30, 2017. http/impl/client/HttpClientBuilder.java in Apache HttpClient 4.3.x before 4.3.1 does not ensure that X509HostnameVerifier is not null, which allows attackers to have unspecified impact via vectors involving hostname verification.
When was CVE-2013-4366 disclosed?
CVE-2013-4366 was first published in the National Vulnerability Database on October 30, 2017, with the most recent update on May 13, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2013-4366 actively exploited?
CVE-2013-4366 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 80.5% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2013-4366?
CVE-2013-4366 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2013-4366?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2013-4366, 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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