CVE-2018-8420

HIGHNVD 8.88.9▲
EchelonGraph scoreHIGH confidence

Score elevated to 8.9 because EPSS predicts 49% probability of exploitation within the next 30 days (top 1.2% of all CVEs). NVD baseline CVSS 8.8 retained for reference. Confidence: see factors.

Triggered by: EPSS exploit prediction ≥85%
Sources: epss, ghsa, nvd
Elevated
8.8
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 49%CVSS: 8.8Exploit: NoneExposed: 0

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

A remote code execution vulnerability exists when the Microsoft XML Core Services MSXML parser processes user input, aka "MS XML Remote Code Execution Vulnerability." This affects Windows 7, Windows Server 2012 R2, Windows RT 8.1, Windows Server 2008, Windows Server 2012, Windows 8.1, Windows Server 2016, Windows Server 2008 R2, Windows 10, Windows 10 Servers.

CVSS v3
8.8
EG Score
8.9(high)
EG Risk
64(Track)
EG Risk 64/100SSVC: 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
Severity89% × 45%
Exploitation49% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS
98.8%
KEV
Not listed

Published

September 13, 2018

Last Modified

November 21, 2024

References (6)

Weakness Classification(1)

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

All Vendor Advisories

(1)

Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.

Data Freshness Timeline

(refreshed 12× in last 7d / 36× 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 01:37 UTCEG score recompute▲ 0.10
  2. 2026-07-22 22:17 UTCEG score recompute
  3. 2026-07-22 14:05 UTCEPSS rescore
  4. 2026-07-21 15:22 UTCEPSS rescore
  5. 2026-07-20 17:04 UTCEPSS rescore
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  7. 2026-07-19 14:28 UTCEPSS rescore
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  17. 2026-07-09 19:06 UTCEPSS rescore
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  20. 2026-07-04 06:28 UTCEPSS rescore
  21. 2026-07-04 06:28 UTCEPSS rescore
  22. 2026-07-01 15:03 UTCEPSS rescore
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  24. 2026-06-30 23:20 UTCEPSS rescore
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  1. 2026-06-29 14:03 UTCEPSS rescore
  2. 2026-06-28 04:53 UTCEPSS rescore
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  4. 2026-06-27 03:06 UTCEPSS rescore
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  6. 2026-06-25 13:47 UTCEPSS rescore
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  10. 2026-06-23 21:30 UTCEPSS rescore
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  14. 2026-06-19 19:23 UTCEPSS rescore
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  16. 2026-06-18 17:50 UTCEPSS rescore
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  21. 2026-06-15 17:45 UTCEPSS rescore
  22. 2026-06-14 23:15 UTCEPSS rescore
  23. 2026-06-14 23:15 UTCEPSS rescore
  24. 2026-06-13 22:58 UTCEPSS rescore
  25. 2026-06-12 23:09 UTCEPSS rescore
  26. 2026-06-12 23:09 UTCEPSS rescore
  27. 2026-06-11 13:57 UTCEPSS rescore
  28. 2026-06-10 22:16 UTCEPSS rescore
  29. 2026-06-05 22:45 UTCEPSS rescore
  30. 2026-06-05 22:45 UTCEPSS rescore
  31. 2026-06-05 06:08 UTCEPSS rescore
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  33. 2026-06-04 13:10 UTCEPSS rescore
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  35. 2026-06-02 20:11 UTCEPSS rescore
  36. 2026-06-01 13:50 UTCEPSS rescore
  37. 2026-05-31 22:29 UTCEPSS rescore
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  39. 2026-05-31 00:14 UTCEPSS rescore
  40. 2026-05-31 00:14 UTCEPSS rescore
  41. 2026-05-29 13:41 UTCEPSS rescore
  42. 2026-05-28 13:43 UTCEPSS rescore
  43. 2026-05-28 13:42 UTCEPSS rescore
  44. 2026-05-28 03:14 UTCEG score recompute
  45. 2026-05-28 03:14 UTCVendor advisory
  46. 2026-05-28 03:14 UTCGHSA enrichment
  47. 2026-05-26 13:42 UTCEPSS rescore
  48. 2026-05-26 13:42 UTCEPSS rescore
  49. 2026-05-26 07:17 UTCEPSS rescore
  50. 2026-05-26 07:17 UTCEPSS rescore

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2018-8420?
CVE-2018-8420 is a high vulnerability published on September 13, 2018. A remote code execution vulnerability exists when the Microsoft XML Core Services MSXML parser processes user input, aka "MS XML Remote Code Execution Vulnerability." This affects Windows 7, Windows Server 2012 R2, Windows RT 8.1, Windows Server 2008, Windows Server 2012, Windows 8.1, Windows…
When was CVE-2018-8420 disclosed?
CVE-2018-8420 was first published in the National Vulnerability Database on September 13, 2018, with the most recent update on November 21, 2024. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2018-8420 actively exploited?
CVE-2018-8420 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 98.8% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2018-8420?
CVE-2018-8420 has a CVSS v3 base score of 8.8 (NVD). EchelonGraph synthesises NVD + CISA KEV + FIRST EPSS + GHSA into a combined EG score of 8.9.
How do I remediate CVE-2018-8420?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2018-8420, 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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