CVE-2021-42278

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 2022-04-11), 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: 70%CVSS: 7.5Exploit: cisa kev · ssvc active · kev ransomware · epss top5pct · epss high · public exploitExposed: 0

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

Active Directory Domain Services Elevation of Privilege 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
70%
EPSS %ILE
99%
KEV
⚠ Exploited

Published

November 10, 2021

Last Modified

October 30, 2025

Advisory Details (2)

Auto-updated Jun 5, 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-2021-42278
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-2021-42278

Weakness Classification(2)

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 59× in last 7d / 335× 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 653 total refreshes for this CVE.

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

Publicly available exploits

(5 references)

Working exploit code is in the public domain (5 GitHub PoCs). Defenders should treat patch urgency accordingly — public PoCs typically lead to mass-exploitation within 24-72 hours.

  • GitHub PoCcybersecurityworks553/noPac-detection
    First seen Dec 27, 2021

    Detection script for CVE-2021-42278 and CVE-2021-42287

    Open source ↗
  • GitHub PoCRidter/noPac
    First seen Dec 13, 2021

    Exploiting CVE-2021-42278 and CVE-2021-42287 to impersonate DA from standard domain user

    Open source ↗
  • GitHub PoCly4k/Pachine
    First seen Dec 13, 2021

    Python implementation for CVE-2021-42278 (Active Directory Privilege Escalation)

    Open source ↗
  • GitHub PoCwaterrr/noPac
    First seen Dec 13, 2021

    Exploiting CVE-2021-42278 and CVE-2021-42287

    Open source ↗
  • GitHub PoCsafebuffer/sam-the-admin
    First seen Dec 11, 2021

    Exploiting CVE-2021-42278 and CVE-2021-42287 to impersonate DA from standard domain user

    Open source ↗

Frequently asked(6)

What is CVE-2021-42278?
CVE-2021-42278 is a critical vulnerability published on November 10, 2021. Active Directory Domain Services Elevation of Privilege Vulnerability
When was CVE-2021-42278 disclosed?
CVE-2021-42278 was first published in the National Vulnerability Database on November 10, 2021, with the most recent update on October 30, 2025. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2021-42278 actively exploited?
Yes. CISA added CVE-2021-42278 to the Known Exploited Vulnerabilities catalog on April 11, 2022, affecting Microsoft Active Directory. KEV listing indicates confirmed exploitation in the wild; this CVE warrants immediate patching attention.
What is the CVSS score of CVE-2021-42278?
CVE-2021-42278 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-2021-42278?
CVE-2021-42278 affects Microsoft Active Directory. 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-2021-42278?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-42278, 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-2021-42278

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