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)
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 138× in last 7d / 571× 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 807 total refreshes for this CVE.

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

Explore the affected products and dependency analysis for CVE-2021-33742

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