CVE-2026-41091

CRITICALPre-NVD 7.89.0▲
EchelonGraph scoreHIGH confidence

Score elevated to 9.0 because this CVE is listed on the CISA Known Exploited Vulnerabilities catalog (added 2026-05-20), indicating real-world exploitation has been confirmed by US federal agencies. the CNA's CVSS baseline 7.8 retained for reference (NVD's own analysis pending). Confidence: HIGH.

Triggered by: CISA KEV (actively exploited)
Sources: cisa_kev, cna:microsoft, epss, ghsa
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: 8%CVSS: 7.8Exploit: cisa kev · ssvc active · public exploitExposed: 0

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

Improper link resolution before file access ('link following') in Microsoft Defender allows an authorized attacker to elevate privileges locally.

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
8%
EPSS %ILE
94%
KEV
⚠ Exploited

Published

May 20, 2026

Last Modified

August 10, 2026

Advisory Details (1)

Auto-updated May 20, 2026
Patch available. Sources: microsoft.
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-2026-41091

Vendor Advisories for CVE-2026-41091(2)

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.

Data Freshness Timeline

(refreshed 97× in last 7d / 400× 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 1,264 total refreshes for this CVE.

  1. 2026-09-05 06:30 UTCVendor advisory
  2. 2026-09-05 06:30 UTCGHSA enrichment
  3. 2026-09-05 02:23 UTCVendor advisory
  4. 2026-09-05 02:23 UTCGHSA enrichment
  5. 2026-09-04 22:15 UTCVendor advisory
  6. 2026-09-04 22:15 UTCGHSA enrichment
  7. 2026-09-04 18:07 UTCEG score recompute
  8. 2026-09-04 18:07 UTCVendor advisory
  9. 2026-09-04 18:07 UTCGHSA enrichment
  10. 2026-09-04 17:38 UTCCISA KEV update
  11. 2026-09-04 13:58 UTCVendor advisory
  12. 2026-09-04 13:58 UTCGHSA enrichment
  13. 2026-09-04 09:50 UTCVendor advisory
  14. 2026-09-04 09:50 UTCGHSA enrichment
  15. 2026-09-04 05:42 UTCEG score recompute
  16. 2026-09-04 05:42 UTCVendor advisory
  17. 2026-09-04 05:42 UTCGHSA enrichment
  18. 2026-09-04 05:06 UTCEPSS rescore
  19. 2026-09-04 01:33 UTCVendor advisory
  20. 2026-09-04 01:33 UTCGHSA enrichment
  21. 2026-09-03 21:26 UTCVendor advisory
  22. 2026-09-03 21:25 UTCGHSA enrichment
  23. 2026-09-03 17:17 UTCVendor advisory
  24. 2026-09-03 17:17 UTCGHSA enrichment
  25. 2026-09-03 13:10 UTCVendor advisory
Show 75 more
  1. 2026-09-03 13:10 UTCGHSA enrichment
  2. 2026-09-03 09:02 UTCVendor advisory
  3. 2026-09-03 09:02 UTCGHSA enrichment
  4. 2026-09-03 04:54 UTCVendor advisory
  5. 2026-09-03 04:54 UTCGHSA enrichment
  6. 2026-09-03 00:44 UTCVendor advisory
  7. 2026-09-03 00:44 UTCGHSA enrichment
  8. 2026-09-02 20:37 UTCVendor advisory
  9. 2026-09-02 20:37 UTCGHSA enrichment
  10. 2026-09-02 17:33 UTCCISA KEV update
  11. 2026-09-02 16:29 UTCEG score recompute
  12. 2026-09-02 16:29 UTCVendor advisory
  13. 2026-09-02 16:29 UTCGHSA enrichment
  14. 2026-09-02 14:12 UTCEPSS rescore
  15. 2026-09-02 12:22 UTCVendor advisory
  16. 2026-09-02 12:22 UTCGHSA enrichment
  17. 2026-09-02 08:13 UTCGHSA enrichment
  18. 2026-09-02 04:06 UTCVendor advisory
  19. 2026-09-02 04:06 UTCGHSA enrichment
  20. 2026-09-01 23:59 UTCVendor advisory
  21. 2026-09-01 23:59 UTCGHSA enrichment
  22. 2026-09-01 19:52 UTCVendor advisory
  23. 2026-09-01 19:52 UTCGHSA enrichment
  24. 2026-09-01 15:45 UTCEG score recompute
  25. 2026-09-01 15:45 UTCVendor advisory
  26. 2026-09-01 15:44 UTCGHSA enrichment
  27. 2026-09-01 13:53 UTCEPSS rescore
  28. 2026-09-01 11:34 UTCVendor advisory
  29. 2026-09-01 11:34 UTCGHSA enrichment
  30. 2026-09-01 07:26 UTCEG score recompute
  31. 2026-09-01 07:26 UTCVendor advisory
  32. 2026-09-01 07:26 UTCGHSA enrichment
  33. 2026-09-01 04:39 UTCEPSS rescore
  34. 2026-09-01 03:18 UTCVendor advisory
  35. 2026-09-01 03:18 UTCGHSA enrichment
  36. 2026-08-31 23:11 UTCVendor advisory
  37. 2026-08-31 23:11 UTCGHSA enrichment
  38. 2026-08-31 19:04 UTCVendor advisory
  39. 2026-08-31 19:04 UTCGHSA enrichment
  40. 2026-08-31 14:56 UTCVendor advisory
  41. 2026-08-31 14:55 UTCGHSA enrichment
  42. 2026-08-31 14:19 UTCCISA KEV update
  43. 2026-08-31 10:46 UTCVendor advisory
  44. 2026-08-31 10:46 UTCGHSA enrichment
  45. 2026-08-31 06:38 UTCVendor advisory
  46. 2026-08-31 06:38 UTCGHSA enrichment
  47. 2026-08-31 02:31 UTCVendor advisory
  48. 2026-08-31 02:31 UTCGHSA enrichment
  49. 2026-08-30 22:23 UTCEG score recompute
  50. 2026-08-30 22:23 UTCVendor advisory
  51. 2026-08-30 22:23 UTCGHSA enrichment
  52. 2026-08-30 19:17 UTCEPSS rescore
  53. 2026-08-30 18:16 UTCVendor advisory
  54. 2026-08-30 18:16 UTCGHSA enrichment
  55. 2026-08-30 14:09 UTCVendor advisory
  56. 2026-08-30 14:09 UTCGHSA enrichment
  57. 2026-08-30 10:01 UTCVendor advisory
  58. 2026-08-30 10:01 UTCGHSA enrichment
  59. 2026-08-30 05:54 UTCVendor advisory
  60. 2026-08-30 05:54 UTCGHSA enrichment
  61. 2026-08-30 01:46 UTCEG score recompute
  62. 2026-08-30 01:46 UTCVendor advisory
  63. 2026-08-30 01:46 UTCGHSA enrichment
  64. 2026-08-30 01:22 UTCEPSS rescore
  65. 2026-08-29 21:38 UTCVendor advisory
  66. 2026-08-29 21:38 UTCGHSA enrichment
  67. 2026-08-29 17:30 UTCVendor advisory
  68. 2026-08-29 17:30 UTCGHSA enrichment
  69. 2026-08-29 13:22 UTCVendor advisory
  70. 2026-08-29 13:21 UTCGHSA enrichment
  71. 2026-08-29 09:14 UTCVendor advisory
  72. 2026-08-29 09:14 UTCGHSA enrichment
  73. 2026-08-29 05:07 UTCVendor advisory
  74. 2026-08-29 05:06 UTCGHSA enrichment
  75. 2026-08-29 00:59 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 PoCtc4dy/CVE-2026-41091-PoC-Exploit
    First seen Jun 20, 2026

    🔥 CVE-2026-41091 SolarFlare | Microsoft Defender LPE exploit. Low-privileged users gain NT AUTHORITY\SYSTEM via Cloud Files API + NTFS junction trickery. Forces Defender to write malicious payloads to System32 with SYSTEM rights. ⚠️ Actively exploited in wild. CVSS 7.8. Patch: Defender Engine 1.1.26040.8. 🛡️ Educational PoC only.

    Open source ↗
  • GitHub PoC0xBlackash/CVE-2026-41091
    First seen May 21, 2026

    CVE-2026-41091

    Open source ↗

Related CVEs(same vendor + same CWE)

Frequently asked(6)

What is CVE-2026-41091?
CVE-2026-41091 is a critical vulnerability published on May 20, 2026. Improper link resolution before file access ('link following') in Microsoft Defender allows an authorized attacker to elevate privileges locally.
When was CVE-2026-41091 disclosed?
CVE-2026-41091 was first published in the National Vulnerability Database on May 20, 2026, 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-2026-41091 actively exploited?
Yes. CISA added CVE-2026-41091 to the Known Exploited Vulnerabilities catalog on May 20, 2026, affecting Microsoft Defender. KEV listing indicates confirmed exploitation in the wild; this CVE warrants immediate patching attention.
What is the CVSS score of CVE-2026-41091?
CVE-2026-41091 has a CVSS v4.0 base score of 7.8 (CNA self-assessment; NVD's own analysis pending). EchelonGraph synthesises NVD + CISA KEV + FIRST EPSS + GHSA into a combined EG score of 9.0.
Which products are affected by CVE-2026-41091?
CVE-2026-41091 affects Microsoft Defender. 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-2026-41091?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-41091, 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-2026-41091

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