CVE-2021-36955

CRITICALNVD 7.89.0▲
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 7.8 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: 4%CVSS: 7.8Exploit: cisa kev · ssvc active · kev ransomware · public exploitExposed: 0

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

Windows Common Log File System Driver Elevation of Privilege Vulnerability

CVSS v3
7.8
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
4%
EPSS %ILE
90%
KEV
⚠ Exploited

Published

September 15, 2021

Last Modified

August 10, 2026

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-2021-36955
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-2021-36955

Vendor Advisories for CVE-2021-36955(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

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 93× in last 7d / 395× 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 1,296 total refreshes for this CVE.

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

Publicly available exploits

(1 reference)

Working exploit code is in the public domain (1 GitHub PoC). Defenders should treat patch urgency accordingly — public PoCs typically lead to mass-exploitation within 24-72 hours.

  • GitHub PoCJiaJinRong12138/CVE-2021-36955-EXP
    First seen Jul 18, 2022

    CVE-2021-36955

    Open source ↗

Related CVEs(same vendor + same CWE)

Frequently asked(6)

What is CVE-2021-36955?
CVE-2021-36955 is a critical vulnerability published on September 15, 2021. Windows Common Log File System Driver Elevation of Privilege Vulnerability
When was CVE-2021-36955 disclosed?
CVE-2021-36955 was first published in the National Vulnerability Database on September 15, 2021, with the most recent update on August 10, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2021-36955 actively exploited?
Yes. CISA added CVE-2021-36955 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-2021-36955?
CVE-2021-36955 has a CVSS v3 base score of 7.8 (NVD). EchelonGraph synthesises NVD + CISA KEV + FIRST EPSS + GHSA into a combined EG score of 9.0.
Which products are affected by CVE-2021-36955?
CVE-2021-36955 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-2021-36955?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-36955, 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-2021-36955

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