CVE-2021-31955

MEDIUMNVD 5.59.0▲
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 5.5 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
5.5
EchelonGraph verdictPatch nowTreat as an emergency — this is being exploited.
  • Actively exploited in the wild (CISA-KEV)
CISA-KEV: ExploitedEPSS: 81%CVSS: 5.5Exploit: NoneExposed: 0

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

Windows Kernel Information Disclosure Vulnerability

CVSS v3
5.5
EG Score
9.0(high)
EPSS
99.6%
KEV
⚠ Exploited

Published

June 8, 2021

Last Modified

October 30, 2025

Advisory Details (2)

Auto-updated Jun 13, 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-2021-31955
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-2021-31955

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 132× in last 7d / 569× 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 907 total refreshes for this CVE.

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

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 PoCApexPredator-InfoSec/forti_shield
    First seen Oct 29, 2025

    A combined POC for CVE-2021-31955, CVE-2015-4077, and CVE-2015-5736

    Open source ↗
  • GitHub PoCfreeide/CVE-2021-31955-POC
    First seen Jun 26, 2021
    Open source ↗

Related CVEs(same vendor + same CWE)

Frequently asked(6)

What is CVE-2021-31955?
CVE-2021-31955 is a medium vulnerability published on June 8, 2021. Windows Kernel Information Disclosure Vulnerability
When was CVE-2021-31955 disclosed?
CVE-2021-31955 was first published in the National Vulnerability Database on June 8, 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-2021-31955 actively exploited?
Yes. CISA added CVE-2021-31955 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-2021-31955?
CVE-2021-31955 has a CVSS v3 base score of 5.5 (NVD). EchelonGraph synthesises NVD + CISA KEV + FIRST EPSS + GHSA into a combined EG score of 9.0.
Which products are affected by CVE-2021-31955?
CVE-2021-31955 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-2021-31955?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-31955, 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-2021-31955

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