Improper link resolution before file access ('link following') in Microsoft Defender allows an authorized attacker to elevate privileges locally.
CVE-2026-41091
“▲” 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.
- 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
A fix is available — apply it.
- CVSS v3
- 7.8
- EG Score
- 9.0CRITICALhigh confidence
- EG Risk
- 75EG 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, 2026Security Update Guide - Microsoft Security Response Center
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-41091Vendor 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.
- 2026-10-19 20:08 UTCEG score recompute
- 2026-10-19 20:08 UTCVendor advisory
- 2026-10-19 20:08 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
- 2026-10-19 16:32 UTCEPSS rescoreEPSS 0.4% · 37th percentile
- 2026-10-18 18:07 UTCEG score recompute
- 2026-10-18 18:07 UTCVendor advisory
- 2026-10-18 18:07 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
- 2026-10-18 16:32 UTCEPSS rescoreEPSS 0.4% · 37th percentile
- 2026-10-18 03:42 UTCEG score recompute
- 2026-10-17 16:34 UTCEPSS rescoreEPSS 0.4% · 37th percentile
- 2026-10-17 16:07 UTCEG score recompute
- 2026-10-17 16:07 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
- 2026-10-16 16:42 UTCEPSS rescoreEPSS 0.4% · 37th percentile
- 2026-10-16 14:08 UTCEG score recompute
- 2026-10-16 14:08 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
- 2026-10-15 16:32 UTCEPSS rescoreEPSS 0.4% · 37th percentile
- 2026-10-15 12:11 UTCEG score recompute
- 2026-10-15 12:11 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
- 2026-10-14 16:33 UTCEPSS rescoreEPSS 0.4% · 36th percentile
- 2026-10-14 10:12 UTCEG score recompute
- 2026-10-14 10:12 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
- 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.4% · 36th percentile
- 2026-10-13 08:13 UTCEG score recompute
- 2026-10-13 08:13 UTCVendor advisory
- 2026-10-13 08:12 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
Show 75 moreShow fewer
- 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.4% · 36th percentile
- 2026-10-12 16:08 UTCEG score recompute
- 2026-10-12 06:15 UTCVendor advisory
- 2026-10-12 06:14 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
- 2026-10-12 02:05 UTCVendor advisory
- 2026-10-12 02:04 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
- 2026-10-11 21:57 UTCVendor advisory
- 2026-10-11 21:57 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
- 2026-10-11 19:51 UTCEG score recompute
- 2026-10-11 17:50 UTCVendor advisory
- 2026-10-11 17:50 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
- 2026-10-11 17:04 UTCEG score recompute
- 2026-10-11 13:48 UTCEPSS rescoreEPSS 0.4% · 36th percentile
- 2026-10-11 13:41 UTCEG score recompute
- 2026-10-11 13:41 UTCVendor advisory
- 2026-10-11 13:40 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
- 2026-10-11 09:31 UTCVendor advisory
- 2026-10-11 09:30 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
- 2026-10-11 05:21 UTCVendor advisory
- 2026-10-11 05:21 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
- 2026-10-11 01:14 UTCVendor advisory
- 2026-10-11 01:14 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
- 2026-10-10 21:04 UTCEG score recompute
- 2026-10-10 21:04 UTCVendor advisory
- 2026-10-10 21:03 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
- 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.4% · 36th percentile
- 2026-10-10 16:54 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
- 2026-10-10 12:45 UTCVendor advisory
- 2026-10-10 12:45 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
- 2026-10-10 08:35 UTCVendor advisory
- 2026-10-10 08:35 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
- 2026-10-10 04:27 UTCVendor advisory
- 2026-10-10 04:27 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
- 2026-10-10 00:20 UTCVendor advisory
- 2026-10-10 00:20 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
- 2026-10-09 20:13 UTCEG score recompute
- 2026-10-09 20:13 UTCVendor advisory
- 2026-10-09 20:12 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
- 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.4% · 36th percentile
- 2026-10-09 16:05 UTCVendor advisory
- 2026-10-09 16:05 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
- 2026-10-09 11:58 UTCVendor advisory
- 2026-10-09 11:58 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
- 2026-10-09 07:49 UTCVendor advisory
- 2026-10-09 07:49 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
- 2026-10-09 03:42 UTCVendor advisory
- 2026-10-09 03:42 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
- 2026-10-08 23:35 UTCVendor advisory
- 2026-10-08 23:35 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
- 2026-10-08 19:28 UTCEG score recompute
- 2026-10-08 19:28 UTCVendor advisory
- 2026-10-08 19:27 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
- 2026-10-08 17:12 UTCEPSS rescoreEPSS 0.4% · 36th percentile
- 2026-10-08 15:20 UTCVendor advisory
- 2026-10-08 15:20 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
- 2026-10-08 11:13 UTCVendor advisory
- 2026-10-08 11:13 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
- 2026-10-08 07:06 UTCVendor advisory
- 2026-10-08 07:06 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
- 2026-10-08 02:58 UTCEG score recompute
- 2026-10-08 02:58 UTCVendor advisory
- 2026-10-08 02:58 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
- 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.4% · 36th percentile
- 2026-10-07 22:50 UTCVendor advisory
- 2026-10-07 22:50 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
- 2026-10-07 18:43 UTCVendor advisory
- 2026-10-07 18:43 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
- 2026-10-07 14:36 UTCVendor advisory
- 2026-10-07 14:35 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
- 2026-10-07 10:27 UTCVendor advisory
- 2026-10-07 10:27 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
- 2026-10-07 06:20 UTCVendor advisory
- 2026-10-07 06:20 UTCGHSA enrichmentGHSA-h776-j9jw-992p · GitHub severity HIGH · GitHub CVSS 7.8
- 2026-10-07 02:13 UTCVendor advisory
- 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-ExploitPublished 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-2026-41091Published May 21, 2026
CVE-2026-41091
Open source ↗
Related CVEs(same CWE)
Frequently asked(6)
What is CVE-2026-41091?
When was CVE-2026-41091 made public?
Is CVE-2026-41091 actively exploited?
What is the CVSS score of CVE-2026-41091?
Which products are affected by CVE-2026-41091?
How do I remediate CVE-2026-41091?
Dependency Blast Radius
Explore the affected products and dependency analysis for CVE-2026-41091
Is Your Infrastructure Affected by CVE-2026-41091?
EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.