CVE-2026-21510

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: 26%CVSS: 8.8Exploit: cisa kev · ssvc active · epss top5pct · public exploitExposed: 0

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

Protection mechanism failure in Windows Shell 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
26%
EPSS %ILE
98%
KEV
⚠ Exploited

Published

February 10, 2026

Last Modified

August 19, 2026

Advisory Details (2)

Auto-updated Jun 2, 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-2026-21510
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-2026-21510

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 99× in last 7d / 409× 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 1,473 total refreshes for this CVE.

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

Publicly available exploits

(2 references)

Working exploit code is in the public domain (2 GitHub PoCs). Defenders should treat patch urgency accordingly — public PoCs typically lead to mass-exploitation within 24-72 hours.

  • GitHub PoCEpSiLoNPoInTOrI/EpSiLoNPoInTlnk
    First seen May 9, 2026

    CVE-2026-21510 LNK generator PoC

    Open source ↗
  • GitHub PoCandreassudo/CVE-2026-21510-CVSS-8.8-Important-Windows-Shell-security-feature-bypass
    First seen Feb 11, 2026

    CVE-2026-21510 (CVSS 8.8, Important) — Windows Shell security feature bypass. An attacker can trick a user into clicking a malicious link or shortcut file to bypass SmartScreen/Shell warnings and execute code without prompts. Publicly disclosed and exploited.

    Open source ↗

Frequently asked(6)

What is CVE-2026-21510?
CVE-2026-21510 is a critical vulnerability published on February 10, 2026. Protection mechanism failure in Windows Shell allows an unauthorized attacker to bypass a security feature over a network.
When was CVE-2026-21510 disclosed?
CVE-2026-21510 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-2026-21510 actively exploited?
Yes. CISA added CVE-2026-21510 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-2026-21510?
CVE-2026-21510 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-2026-21510?
CVE-2026-21510 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-2026-21510?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-21510, 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-2026-21510

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