CVE-2018-6334

CRITICALNVD 9.89.8—
EchelonGraph scoreMEDIUM confidence

Score 9.8 from GitHub Security Advisory (severity: CRITICAL) published 2022-05-13. NVD baseline CVSS 9.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: ghsa, 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.

Multipart-file uploads call variables to be improperly registered in the global scope. In cases where variables are not declared explicitly before being used this can lead to unexpected behavior. This affects all supported versions of HHVM prior to the patch (3.25.1, 3.24.5, and 3.21.9 and below).

CVSS v3
9.8
EG Score
9.8(medium)
EPSS
77.7%
KEV
Not listed

Published

December 31, 2018

Last Modified

May 6, 2025

Advisory Details (2)

Auto-updated May 25, 2026
Upstream fix merged — awaiting tagged release. Sources: github_commit.
generic

HHVM 3.25.2, HHVM 3.24.6, and 3.21.10 (CVE-2018-6334) | HHVM

https://hhvm.com/blog/2018/03/30/hhvm-3.25.2.html
github_commit

commit 6937de5544c3 (facebook/hhvm)

Fix landed in facebook/hhvm commit 6937de5544c3 — awaiting tagged release

https://github.com/facebook/hhvm/commit/6937de5544c3eead3466b75020d8382080ed0cff

Weakness Classification(2)

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

Data Freshness Timeline

(refreshed 10× 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. 2026-07-22 14:05 UTCEPSS rescore
  2. 2026-07-21 15:22 UTCEPSS rescore
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  15. 2026-07-12 19:37 UTCOSV refresh
  16. 2026-07-12 05:43 UTCEPSS rescore
  17. 2026-07-09 19:06 UTCEPSS rescore
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  1. 2026-07-04 06:28 UTCEPSS rescore
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  5. 2026-06-30 23:20 UTCEPSS rescore
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  7. 2026-06-29 14:03 UTCEPSS rescore
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  17. 2026-06-24 04:29 UTCOSV refresh
  18. 2026-06-23 21:30 UTCEPSS rescore
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  20. 2026-06-22 14:23 UTCEPSS rescore
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  26. 2026-06-19 19:23 UTCEPSS rescore
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  37. 2026-06-12 23:09 UTCEPSS rescore
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  39. 2026-06-11 13:57 UTCEPSS rescore
  40. 2026-06-10 22:16 UTCEPSS rescore
  41. 2026-06-10 13:19 UTCEPSS rescore
  42. 2026-06-08 14:14 UTCEPSS rescore
  43. 2026-06-07 15:22 UTCEPSS rescore
  44. 2026-06-07 15:22 UTCEPSS rescore
  45. 2026-06-07 09:00 UTCOSV refresh
  46. 2026-06-06 13:45 UTCEPSS rescore
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  48. 2026-06-05 22:45 UTCEPSS rescore
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  50. 2026-06-05 06:08 UTCEPSS rescore
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  52. 2026-06-04 13:10 UTCEPSS rescore
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  54. 2026-06-02 20:11 UTCEPSS rescore
  55. 2026-06-01 13:50 UTCEPSS rescore
  56. 2026-05-31 22:29 UTCEPSS rescore
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  63. 2026-05-27 13:38 UTCEPSS rescore
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  66. 2026-05-26 07:17 UTCEPSS rescore
  67. 2026-05-26 07:17 UTCEPSS rescore
  68. 2026-05-23 02:44 UTCEG score recompute
  69. 2026-05-23 02:44 UTCGHSA enrichment

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Frequently asked(5)

What is CVE-2018-6334?
CVE-2018-6334 is a critical vulnerability published on December 31, 2018. Multipart-file uploads call variables to be improperly registered in the global scope. In cases where variables are not declared explicitly before being used this can lead to unexpected behavior. This affects all supported versions of HHVM prior to the patch (3.25.1, 3.24.5, and 3.21.9 and below).
When was CVE-2018-6334 disclosed?
CVE-2018-6334 was first published in the National Vulnerability Database on December 31, 2018, with the most recent update on May 6, 2025. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2018-6334 actively exploited?
CVE-2018-6334 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 77.7% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2018-6334?
CVE-2018-6334 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2018-6334?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2018-6334, 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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