CVE-2017-8558

HIGHNVD 7.88.1▲
EchelonGraph scoreHIGH confidence

Score elevated to 8.1 because EPSS predicts 44% probability of exploitation within the next 30 days (98th percentile of EPSS-scored CVEs). NVD baseline CVSS 7.8 retained for reference. Confidence: see factors.

Triggered by: EPSS exploit prediction ≥85%
Sources: epss, ghsa, nvd
Weaponized
8.1EG
EchelonGraph verdictPatch this weekExploitation is likely or a public exploit exists.
  • Public exploit code is available (Exploit-DB (verified), epss top5pct, public exploit)
CISA-KEV: Not listedEPSS PROB: 44%CVSS: 7.8Exploit: Exploit-DB (verified) · epss top5pct · public exploitExposed services: Not assessed

A fix is available — apply it.

The Microsoft Malware Protection Engine running on Microsoft Forefront and Microsoft Defender on 32-bit versions of Microsoft Windows Server 2008 SP2 and R2 SP1, Windows 7 SP1, Windows 8.1, Windows Server 2012 Gold and R2, Windows RT 8.1, Windows 10 Gold, 1511, 1607, and 1703 does not properly scan a specially crafted file leading to memory corruption. aka "Microsoft Malware Protection Engine Remote Code Execution Vulnerability".

CVSS v3
7.8
EG Score
8.1HIGHhigh confidence
EG Risk
67
EG Risk 67/100CISA SSVC

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
Severity81% × 45%
Exploitation65% × 40%
Automatability30% × 15%
CISA SSVC: Track at low or medium mission impact; Track* or Attend at high (mission-essential systems).
Action: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
EPSS PROB
44%
EPSS %ILE
98th
KEV
Not listed

CISA SSVCTrack at low or medium mission impact; Track* or Attend at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation public PoC (EG-KEV: weaponized) · Automatable unknown (not published for this CVE) · Technical impact partial (CVSS below 9.0). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

Published

June 29, 2017

Last Modified

June 17, 2026

Advisory Details (3)

Auto-updated Sep 30, 2026
🔬 Proof of concept available. Patch available. Sources: microsoft.
generic🟡 PoC Available

Microsoft MsMpEng - mpengine x86 Emulator Heap Corruption in VFS API - Windows dos Exploit

https://www.exploit-db.com/exploits/42264/
microsoft Patch Available

Security Update Guide - Microsoft Security Response Center

Security Update Guide - Microsoft Security Response Center. Patch available via Microsoft Security Update

https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2017-8558
generic

CVE-2017-8558 - PSIRT.COM

http://www.securityfocus.com/bid/99262

Vendor Advisories for CVE-2017-8558(1)

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

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 4× in last 7d / 18× 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.

Showing the most recent 100 of 153 total refreshes for this CVE.

  1. 2026-10-03 14:21 UTCEPSS rescore
  2. 2026-10-03 14:21 UTCEPSS rescore
  3. 2026-09-30 14:59 UTCEPSS rescore
  4. 2026-09-30 09:42 UTCEG score recompute
  5. 2026-09-26 15:53 UTCEPSS rescore
  6. 2026-09-24 13:59 UTCEPSS rescore
  7. 2026-09-23 13:42 UTCEPSS rescore
  8. 2026-09-21 20:27 UTCEPSS rescore
  9. 2026-09-20 20:09 UTCEPSS rescore
  10. 2026-09-19 15:36 UTCEPSS rescore
  11. 2026-09-17 19:22 UTCEPSS rescore
  12. 2026-09-17 19:22 UTCEPSS rescore
  13. 2026-09-15 03:05 UTCEPSS rescore
  14. 2026-09-12 14:56 UTCEPSS rescore
  15. 2026-09-11 09:31 UTCEPSS rescore
  16. 2026-09-07 15:56 UTCEPSS rescore
  17. 2026-09-05 15:24 UTCEPSS rescore
  18. 2026-09-04 13:56 UTCEPSS rescore
  19. 2026-09-04 05:02 UTCEPSS rescore
  20. 2026-09-02 14:07 UTCEPSS rescore
  21. 2026-09-02 14:07 UTCEPSS rescore
  22. 2026-09-01 03:31 UTCEPSS rescore
  23. 2026-08-30 19:13 UTCEPSS rescore
  24. 2026-08-28 21:36 UTCEPSS rescore
  25. 2026-08-27 14:21 UTCEPSS rescore
Show 75 more
  1. 2026-08-26 14:41 UTCEPSS rescore
  2. 2026-08-25 13:44 UTCEPSS rescore
  3. 2026-08-23 00:14 UTCEPSS rescore
  4. 2026-08-21 23:44 UTCEPSS rescore
  5. 2026-08-19 16:59 UTCEPSS rescore
  6. 2026-08-18 13:43 UTCEPSS rescore
  7. 2026-08-16 14:51 UTCEPSS rescore
  8. 2026-08-16 02:10 UTCEPSS rescore
  9. 2026-08-15 01:26 UTCEPSS rescore
  10. 2026-08-12 13:46 UTCEPSS rescore
  11. 2026-08-09 13:42 UTCEPSS rescore
  12. 2026-08-08 16:32 UTCEPSS rescore
  13. 2026-08-07 16:22 UTCEPSS rescore
  14. 2026-08-06 13:42 UTCEPSS rescore
  15. 2026-08-06 13:42 UTCEPSS rescore
  16. 2026-08-01 04:12 UTCEPSS rescore
  17. 2026-07-30 16:24 UTCEPSS rescore
  18. 2026-07-30 01:26 UTCEPSS rescore
  19. 2026-07-28 15:32 UTCEPSS rescore
  20. 2026-07-26 14:51 UTCEPSS rescore
  21. 2026-07-26 14:51 UTCEPSS rescore
  22. 2026-07-23 14:15 UTCEPSS rescore
  23. 2026-07-23 01:30 UTCEG score recompute▲ 0.30
  24. 2026-07-22 22:10 UTCEG score recompute
  25. 2026-07-22 14:04 UTCEPSS rescore
  26. 2026-07-21 15:21 UTCEPSS rescore
  27. 2026-07-20 17:04 UTCEPSS rescore
  28. 2026-07-20 17:04 UTCEPSS rescore
  29. 2026-07-19 02:26 UTCEPSS rescore
  30. 2026-07-19 02:26 UTCEPSS rescore
  31. 2026-07-18 10:01 UTCEPSS rescore
  32. 2026-07-16 16:59 UTCEPSS rescore
  33. 2026-07-16 16:59 UTCEPSS rescore
  34. 2026-07-15 16:55 UTCEPSS rescore
  35. 2026-07-15 16:54 UTCEPSS rescore
  36. 2026-07-15 01:56 UTCEPSS rescore
  37. 2026-07-15 01:56 UTCEPSS rescore
  38. 2026-07-13 22:26 UTCEPSS rescore
  39. 2026-07-13 22:26 UTCEPSS rescore
  40. 2026-07-12 05:43 UTCEPSS rescore
  41. 2026-07-11 08:24 UTCEPSS rescore
  42. 2026-07-09 19:06 UTCEPSS rescore
  43. 2026-07-08 15:11 UTCEPSS rescore
  44. 2026-07-06 16:24 UTCEPSS rescore
  45. 2026-07-06 16:24 UTCEPSS rescore
  46. 2026-07-05 02:27 UTCEPSS rescore
  47. 2026-07-02 16:54 UTCEPSS rescore
  48. 2026-07-01 15:03 UTCEPSS rescore
  49. 2026-06-28 14:04 UTCEPSS rescore
  50. 2026-06-28 04:53 UTCEPSS rescore
  51. 2026-06-28 04:53 UTCEPSS rescore
  52. 2026-06-27 03:06 UTCEPSS rescore
  53. 2026-06-25 13:47 UTCEPSS rescore
  54. 2026-06-24 14:02 UTCEPSS rescore
  55. 2026-06-24 14:02 UTCEPSS rescore
  56. 2026-06-23 21:30 UTCEPSS rescore
  57. 2026-06-23 21:30 UTCEPSS rescore
  58. 2026-06-21 14:54 UTCEPSS rescore
  59. 2026-06-21 14:54 UTCEPSS rescore
  60. 2026-06-21 01:57 UTCEPSS rescore
  61. 2026-06-21 01:57 UTCEPSS rescore
  62. 2026-06-18 17:50 UTCEPSS rescore
  63. 2026-06-17 17:50 UTCEPSS rescore
  64. 2026-06-16 17:50 UTCEPSS rescore
  65. 2026-06-15 17:45 UTCEPSS rescore
  66. 2026-06-13 22:58 UTCEPSS rescore
  67. 2026-06-13 22:57 UTCEPSS rescore
  68. 2026-06-12 23:09 UTCEPSS rescore
  69. 2026-06-12 23:09 UTCEPSS rescore
  70. 2026-06-11 13:57 UTCEPSS rescore
  71. 2026-06-10 22:15 UTCEPSS rescore
  72. 2026-06-10 13:19 UTCEPSS rescore
  73. 2026-06-08 14:14 UTCEPSS rescore
  74. 2026-06-08 14:14 UTCEPSS rescore
  75. 2026-06-07 15:22 UTCEPSS rescore

Publicly available exploits

(1 reference)

Working exploit code is in the public domain (1 Exploit-DB entry). Defenders should treat patch urgency accordingly — public PoCs typically lead to mass-exploitation within 24-72 hours.

  • Exploit-DBEDB-42264✓ verified
    First seen Jun 27, 2017

    Microsoft MsMpEng - mpengine x86 Emulator Heap Corruption in VFS API

    Open source ↗

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2017-8558?
CVE-2017-8558 is a high vulnerability published on June 29, 2017. The Microsoft Malware Protection Engine running on Microsoft Forefront and Microsoft Defender on 32-bit versions of Microsoft Windows Server 2008 SP2 and R2 SP1, Windows 7 SP1, Windows 8.1, Windows Server 2012 Gold and R2, Windows RT 8.1, Windows 10 Gold, 1511, 1607, and 1703 does not properly scan…
When was CVE-2017-8558 disclosed?
CVE-2017-8558 was first published on June 29, 2017, with the most recent update on June 17, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2017-8558 actively exploited?
CVE-2017-8558 is not currently on CISA's Known Exploited Vulnerabilities catalog. EchelonGraph's EG-KEV model classifies it as weaponized: a functional public exploit exists. FIRST EPSS estimates a 44% probability of exploitation in the next 30 days (98th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2017-8558?
CVE-2017-8558 has a CVSS v3 base score of 7.8 (NVD). EchelonGraph synthesises NVD + CISA KEV + FIRST EPSS + GHSA into a combined EG score of 8.1 (HIGH).
How do I remediate CVE-2017-8558?
A fix for CVE-2017-8558 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2017-8558 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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