CVE-2021-33742

CRITICALNVD 7.59.0▲
EchelonGraph scoreHIGH confidence

Score elevated to 9.0 because this CVE is listed on the CISA Known Exploited Vulnerabilities catalog (added 2021-11-03), indicating real-world exploitation has been confirmed by US federal agencies. NVD baseline CVSS 7.5 retained for reference. Confidence: HIGH.

Triggered by: CISA KEV (actively exploited)
Sources: cisa_kev, epss, ghsa, nvd
Trending — 5 sources updated this weekExploited in the wild
9.0EG
EchelonGraph verdictPatch nowTreat as an emergency — this is being exploited.
  • Actively exploited in the wild (CISA-KEV)
CISA-KEV: ExploitedEPSS PROB: 59%CVSS: 7.5Exploit: cisa kev · ssvc active · epss top5pct · epss highExposed: 0

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

Windows MSHTML Platform Remote Code Execution Vulnerability

CVSS v3
7.5
EG Score
9.0(high)
EG Risk
81(Attend)
EG Risk 81/100SSVC: Attend

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
Severity90% × 45%
Exploitation100% × 40%
Automatability0% × 15%
Action: Remediate soon — notable exploitation risk.
EPSS PROB
59%
EPSS %ILE
99%
KEV
⚠ Exploited

Published

June 8, 2021

Last Modified

October 29, 2025

Advisory Details (2)

Auto-updated Jun 4, 2026
⚠️ Active exploitation confirmed. Patch available. Sources: microsoft, cisa.
cisa Patch Available🔴 Active Exploitation

Known Exploited Vulnerabilities Catalog | CISA

Known Exploited Vulnerabilities Catalog | CISA. Listed in CISA Known Exploited Vulnerabilities catalog.

https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-33742
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-2021-33742

Weakness Classification(3)

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 100× in last 7d / 404× 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 1,135 total refreshes for this CVE.

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

Frequently asked(6)

What is CVE-2021-33742?
CVE-2021-33742 is a critical vulnerability published on June 8, 2021. Windows MSHTML Platform Remote Code Execution Vulnerability
When was CVE-2021-33742 disclosed?
CVE-2021-33742 was first published in the National Vulnerability Database on June 8, 2021, with the most recent update on October 29, 2025. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2021-33742 actively exploited?
Yes. CISA added CVE-2021-33742 to the Known Exploited Vulnerabilities catalog on November 3, 2021, affecting Microsoft Windows. KEV listing indicates confirmed exploitation in the wild; this CVE warrants immediate patching attention.
What is the CVSS score of CVE-2021-33742?
CVE-2021-33742 has a CVSS v3 base score of 7.5 (NVD). EchelonGraph synthesises NVD + CISA KEV + FIRST EPSS + GHSA into a combined EG score of 9.0.
Which products are affected by CVE-2021-33742?
CVE-2021-33742 affects Microsoft Windows. The full affected-products list, including version ranges and fixed versions, is shown in the Affected Packages section of this page.
How do I remediate CVE-2021-33742?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-33742, 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.

Dependency Blast Radius

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