CVE-2026-41091

CRITICALPre-NVD 7.89.0
EchelonGraph scoreHIGH confidence

“▲” beside the score: it is higher than the CVSS score beside it.

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). The 9.0 is the floor for confirmed exploitation, not an impact rating: this CVE's impact severity (EG Severity) is CVSS 7.8 HIGH under GitHub Security Advisory CVSS. Confidence: HIGH.

Triggered by: CISA KEV (actively exploited)
Sources: CISA Known Exploited Vulnerabilities catalog, the CNA's CVSS, EPSS, GitHub Security Advisory
Trending — 4 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) — the reason this is sooner than the SSVC decision on this page at low or medium mission impact
CISA-KEV: ExploitedEPSS PROB: 0.4%CVSS: 7.8Exploit: Public PoCExposed services: Not assessed

A fix is available — apply it.

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
9.0CRITICALhigh confidence
EG Risk
75
EG Risk 75/100

EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.

How it’s computed (value × EchelonGraph’s weight)
Severity78% × 45%
Impact severity (EG Severity): CVSS 7.8 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation100% × 40%
Fixed at 100% for a CISA KEV listing: EchelonGraph's rule.
Automatability0% × 15%
CISA's SSVC Automatable value: no (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low, Attend at medium and Act at high mission impact.
Exploitation active (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: A fix is available. Apply it within your standard update timelines at low, sooner than that at medium and as soon as possible at high mission impact.
EPSS PROB
0.4%
EPSS %ILE
37th
KEV
⚠ Exploited

What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)

The EG score (9.0): severity, escalated by confirmed exploitation. This CVE's 9.0 is the CISA KEV floor for confirmed exploitation, not an impact rating: its impact severity (EG Severity) is CVSS 7.8 HIGH.

EG Severity
7.8 HIGHCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
EG Likelihood
0.4% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-19). FIRST's exploitation probability, not an EchelonGraph model.
Confirmed exploitation
CISA KEV and EG-KEV Tier 1 (exploited in the wild)Reported apart from the likelihood: an observed fact, not a probability.
EG Priority
SSVC Attend at medium mission impactTrack at low, Attend at medium and Act at high mission impact.CISA BOD 26-04: 3 days & forensic triage if the affected system is publicly exposed; 14 days if it is not.Each input and its source: the SSVC and BOD 26-04 blocks below.

SSVC (CISA's decision table, applied by EchelonGraph)Track at low, Attend at medium and Act at high mission impact.

A fix is available. Apply it within your standard update timelines at low, sooner than that at medium and as soon as possible at high mission impact.

Exploitation active (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)3 days & forensic triage if the affected system is publicly exposed; 14 days if it is not.

In CISA KEV yes (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

CISA required action“Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.”

Quoted verbatim from CISA's Known Exploited Vulnerabilities catalog. CISA directs it at US federal civilian executive branch agencies under Binding Operational Directive (BOD) 26-04, which replaced BOD 22-01 on 10 June 2026; it is not EchelonGraph's advice. CISA's notes: https://msrc.microsoft.com/update-guide/en-US/vulnerability/CVE-2026-41091 · https://nvd.nist.gov/vuln/detail/CVE-2026-41091

Published

May 20, 2026

Last Modified

August 10, 2026

Advisory Details (1)

Auto-updated Oct 19, 2026
⚠️ Actively exploited (CISA KEV, CISA Vulnrichment). Patch available. Sources: microsoft.
Microsoft

Security Update Guide - Microsoft Security Response Center

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 22× in last 7d / 328× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. 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. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.

Showing the most recent 100 of 1,793 refreshes on record for this CVE.

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. None are among the latest 100 rows. The 1,693 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-10-19 20:08 UTCEG score recompute
  2. 2026-10-19 20:08 UTCVendor advisory
  3. 2026-10-19 20:08 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
  4. 2026-10-19 16:32 UTCEPSS rescoreEPSS 0.4% · 37th percentile
  5. 2026-10-18 18:07 UTCEG score recompute
  6. 2026-10-18 18:07 UTCVendor advisory
  7. 2026-10-18 18:07 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
  8. 2026-10-18 16:32 UTCEPSS rescoreEPSS 0.4% · 37th percentile
  9. 2026-10-18 03:42 UTCEG score recompute
  10. 2026-10-17 16:34 UTCEPSS rescoreEPSS 0.4% · 37th percentile
  11. 2026-10-17 16:07 UTCEG score recompute
  12. 2026-10-17 16:07 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
  13. 2026-10-16 16:42 UTCEPSS rescoreEPSS 0.4% · 37th percentile
  14. 2026-10-16 14:08 UTCEG score recompute
  15. 2026-10-16 14:08 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
  16. 2026-10-15 16:32 UTCEPSS rescoreEPSS 0.4% · 37th percentile
  17. 2026-10-15 12:11 UTCEG score recompute
  18. 2026-10-15 12:11 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
  19. 2026-10-14 16:33 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  20. 2026-10-14 10:12 UTCEG score recompute
  21. 2026-10-14 10:12 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
  22. 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  23. 2026-10-13 08:13 UTCEG score recompute
  24. 2026-10-13 08:13 UTCVendor advisory
  25. 2026-10-13 08:12 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
Show 75 more
  1. 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  2. 2026-10-12 16:08 UTCEG score recompute
  3. 2026-10-12 06:15 UTCVendor advisory
  4. 2026-10-12 06:14 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
  5. 2026-10-12 02:05 UTCVendor advisory
  6. 2026-10-12 02:04 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
  7. 2026-10-11 21:57 UTCVendor advisory
  8. 2026-10-11 21:57 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
  9. 2026-10-11 19:51 UTCEG score recompute
  10. 2026-10-11 17:50 UTCVendor advisory
  11. 2026-10-11 17:50 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
  12. 2026-10-11 17:04 UTCEG score recompute
  13. 2026-10-11 13:48 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  14. 2026-10-11 13:41 UTCEG score recompute
  15. 2026-10-11 13:41 UTCVendor advisory
  16. 2026-10-11 13:40 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
  17. 2026-10-11 09:31 UTCVendor advisory
  18. 2026-10-11 09:30 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
  19. 2026-10-11 05:21 UTCVendor advisory
  20. 2026-10-11 05:21 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
  21. 2026-10-11 01:14 UTCVendor advisory
  22. 2026-10-11 01:14 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
  23. 2026-10-10 21:04 UTCEG score recompute
  24. 2026-10-10 21:04 UTCVendor advisory
  25. 2026-10-10 21:03 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
  26. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  27. 2026-10-10 16:54 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
  28. 2026-10-10 12:45 UTCVendor advisory
  29. 2026-10-10 12:45 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
  30. 2026-10-10 08:35 UTCVendor advisory
  31. 2026-10-10 08:35 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
  32. 2026-10-10 04:27 UTCVendor advisory
  33. 2026-10-10 04:27 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
  34. 2026-10-10 00:20 UTCVendor advisory
  35. 2026-10-10 00:20 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
  36. 2026-10-09 20:13 UTCEG score recompute
  37. 2026-10-09 20:13 UTCVendor advisory
  38. 2026-10-09 20:12 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
  39. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  40. 2026-10-09 16:05 UTCVendor advisory
  41. 2026-10-09 16:05 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
  42. 2026-10-09 11:58 UTCVendor advisory
  43. 2026-10-09 11:58 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
  44. 2026-10-09 07:49 UTCVendor advisory
  45. 2026-10-09 07:49 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
  46. 2026-10-09 03:42 UTCVendor advisory
  47. 2026-10-09 03:42 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
  48. 2026-10-08 23:35 UTCVendor advisory
  49. 2026-10-08 23:35 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
  50. 2026-10-08 19:28 UTCEG score recompute
  51. 2026-10-08 19:28 UTCVendor advisory
  52. 2026-10-08 19:27 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
  53. 2026-10-08 17:12 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  54. 2026-10-08 15:20 UTCVendor advisory
  55. 2026-10-08 15:20 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
  56. 2026-10-08 11:13 UTCVendor advisory
  57. 2026-10-08 11:13 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
  58. 2026-10-08 07:06 UTCVendor advisory
  59. 2026-10-08 07:06 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
  60. 2026-10-08 02:58 UTCEG score recompute
  61. 2026-10-08 02:58 UTCVendor advisory
  62. 2026-10-08 02:58 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
  63. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  64. 2026-10-07 22:50 UTCVendor advisory
  65. 2026-10-07 22:50 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
  66. 2026-10-07 18:43 UTCVendor advisory
  67. 2026-10-07 18:43 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
  68. 2026-10-07 14:36 UTCVendor advisory
  69. 2026-10-07 14:35 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
  70. 2026-10-07 10:27 UTCVendor advisory
  71. 2026-10-07 10:27 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
  72. 2026-10-07 06:20 UTCVendor advisory
  73. 2026-10-07 06:20 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
  74. 2026-10-07 02:13 UTCVendor advisory
  75. 2026-10-07 02:13 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8

Publicly available exploits

(2 references)

Public exploit code is referenced for this CVE (2 GitHub PoCs). Defenders should treat patch urgency accordingly.

  • GitHub PoCtc4dy/CVE-2026-41091-PoC-Exploit
    Published 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
    Published May 21, 2026

    CVE-2026-41091

    Open source ↗

Frequently asked(6)

What is CVE-2026-41091?
CVE-2026-41091 is a critical-severity vulnerability; its CVE record was 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 made public?
CVE-2026-41091 was made public on May 19, 2026: that is the date its CVE record's CNA, Microsoft Corporation, gives for when the vulnerability was made public. The CVE record itself was published on May 20, 2026. EchelonGraph's copy of the record carries a last-modified date of August 10, 2026; the record at its source may have been updated since.
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 attention. A fix is available. Apply it.
What is the CVSS score of CVE-2026-41091?
CVE-2026-41091 has a CVSS base score of 7.8 (the CNA's own assessment, by microsoft; NVD's own analysis pending). EchelonGraph synthesises NVD + CISA KEV + FIRST EPSS + GHSA into a combined EG score of 9.0 (CRITICAL).
Which products are affected by CVE-2026-41091?
CVE-2026-41091 affects Microsoft Defender.
How do I remediate CVE-2026-41091?
A fix for CVE-2026-41091 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-41091 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

Explore the affected products and dependency analysis for CVE-2026-41091

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