CVE-2026-21513

CRITICALNVD 8.89.0▲
EchelonGraph scoreHIGH confidence

Score elevated to 9.0 because this CVE is listed on the CISA Known Exploited Vulnerabilities catalog (added 2026-02-10), indicating real-world exploitation has been confirmed by US federal agencies. NVD baseline CVSS 8.8 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: 16%CVSS: 8.8Exploit: cisa kev · ssvc active · epss top5pctExposed: 0

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

Protection mechanism failure in MSHTML Framework allows an unauthorized attacker to bypass a security feature over a network.

CVSS v3
8.8
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
16%
EPSS %ILE
97%
KEV
⚠ Exploited

Published

February 10, 2026

Last Modified

August 19, 2026

Advisory Details (4)

Auto-updated Jun 1, 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-2026-21513
generic🔴 Active Exploitation

CVE-2026-21513 Mitigation Script - Security Feature Bypass Vulnerability in MSHTML Framework - vsociety

https://www.vicarius.io/vsociety/posts/cve-2026-21513-mitigation-script-security-feature-bypass-vulnerability-in-mshtml-framework
generic🔴 Active Exploitation

CVE-2026-21513 Detection Script - Security Feature Bypass Vulnerability in MSHTML Framework - vsociety

https://www.vicarius.io/vsociety/posts/cve-2026-21513-detection-script-security-feature-bypass-vulnerability-in-mshtml-framework
microsoft Patch Available

Security Update Guide - Microsoft Security Response Center

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

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21513

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 103× in last 7d / 437× 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 1,564 total refreshes for this CVE.

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

Frequently asked(6)

What is CVE-2026-21513?
CVE-2026-21513 is a critical vulnerability published on February 10, 2026. Protection mechanism failure in MSHTML Framework allows an unauthorized attacker to bypass a security feature over a network.
When was CVE-2026-21513 disclosed?
CVE-2026-21513 was first published in the National Vulnerability Database on February 10, 2026, with the most recent update on August 19, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-21513 actively exploited?
Yes. CISA added CVE-2026-21513 to the Known Exploited Vulnerabilities catalog on February 10, 2026, affecting Microsoft Windows. KEV listing indicates confirmed exploitation in the wild; this CVE warrants immediate patching attention.
What is the CVSS score of CVE-2026-21513?
CVE-2026-21513 has a CVSS v3 base score of 8.8 (NVD). EchelonGraph synthesises NVD + CISA KEV + FIRST EPSS + GHSA into a combined EG score of 9.0.
Which products are affected by CVE-2026-21513?
CVE-2026-21513 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-2026-21513?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-21513, 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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