CVE-2021-33742

HIGHNVD 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
7.5
EchelonGraph verdictPatch nowTreat as an emergency — this is being exploited.
  • Actively exploited in the wild (CISA-KEV)
CISA-KEV: ExploitedEPSS: 59%CVSS: 7.5Exploit: NoneExposed: 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)
EPSS
99.0%
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 / 406× 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 709 total refreshes for this CVE.

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

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Frequently asked(6)

What is CVE-2021-33742?
CVE-2021-33742 is a high 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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