What is CVE-2026-41091?

CVE-2026-41091 is a high-severity vulnerability in Microsoft Malware Protection Engine, classified under Improper Link Resolution Before File Access. CVSS score: 7.8/10. Published 2026-05-20.

How severe is CVE-2026-41091?

High severity. CVSS v3 base score is 7.8 out of 10.

Is CVE-2026-41091 known to be exploited?

Yes. CVE-2026-41091 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2026-05-20), indicating it is being actively exploited. 5 public proof-of-concept repositories are indexed.

Vulnerability in Microsoft Malware Protection Engine

CVE-2026-41091

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

Published 2026-05-20 · last modified 2026-07-24.

CVSS v3 metric

CVSS v3 base score 7.8 (High). Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.004 (37.1th percentile), scored 2026-10-19.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 37th percentile — 37.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.082 · newest: 0.004 · change: -0.078

Affected products

Microsoft Malware Protection Engine
Microsoft Malware Protection Engine — versions 1.1.0.0

Weakness classification (CWE)

CWE-59 — Improper Link Resolution Before File Access

CISA KEV (Known Exploited Vulnerabilities)

This CVE is on the CISA KEV catalog, added on 2026-05-20. CISA KEV inclusion means CISA has confirmed in-the-wild exploitation; US federal agencies are required to remediate within a published due date.

BOD 22-01 due date: 2026-06-03.

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.

Public proof-of-concept exploits

References

Microsoft Defender Elevation of Privilege Vulnerability (vendor-advisory, patch, Vendor Advisory)
134c704f-9b21-4f2e-91b3-4a467353bcc0 (US Government Resource, Third Party Advisory)

Frequently asked questions

What is CVE-2026-41091?: CVE-2026-41091 is a high-severity vulnerability in Microsoft Malware Protection Engine, classified under Improper Link Resolution Before File Access. CVSS score: 7.8/10. Published 2026-05-20.
How severe is CVE-2026-41091?: High severity. CVSS v3 base score is 7.8 out of 10.
Is CVE-2026-41091 known to be exploited?: Yes. CVE-2026-41091 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2026-05-20), indicating it is being actively exploited. 5 public proof-of-concept repositories are indexed.