CVE-2026-41091
HighExploitedPublic exploitMicrosoft Defender Elevation of Privilege Vulnerability
Published May 20, 2026 · Updated Aug 10, 2026 · Also known as EUVD-2026-31101, GHSA-h776-j9jw-992p
Key Facts
Patch immediately- CVE-2026-41091 is a high-severity vulnerability (CVSS 7.8 v3.1) affecting Malware Protection Engine (Microsoft).
- It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since May 19, 2026. Public exploit code is available.
- EPSS estimates a 0.4% probability of exploitation in the next 30 days.
- Fixed versions are available, including Malware Protection Engine 1.1.26040.8.
- Brandefense priority: patch immediately, because it is listed as exploited in the wild.
CVSS v3.1
7.8
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
EPSS (30-day exploit likelihood)
0.4%
Exploited in the wild
Yes
4 catalog listings
Public exploit code
Available
Proof-of-concept or weaponized module
Get the full CVE-2026-41091 brief as a PDF
Every affected product and fixed release, exploitation status and a first 24 hours response checklist, emailed within minutes.
Description
Improper link resolution before file access ('link following') in Microsoft Defender allows an authorized attacker to elevate privileges locally.
Known-Exploited Catalog Listings
| Catalog | Added | Remediation due | Ransomware use |
|---|---|---|---|
| CISA KEV | May 20, 2026 | Jun 3, 2026 | Not reported |
| Industry KEV feed | May 19, 2026 | Jun 3, 2026 | Not reported |
| CIRCL KEV | May 20, 2026 | Jun 3, 2026 | Not reported |
| ENISA EUVD | May 20, 2026 | n/a | Not reported |
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.
Affected Products
3 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| Malware Protection EngineMicrosoft | >= 1.1.0.0 | 1.1.26040.8 |
Patched Releases
Malware Protection Engine
1.1.26040.8
Timeline
Added to Industry KEV feed
May 19, 2026
Publicly disclosed
May 20, 2026
Added to CISA KEV
May 20, 2026
Added to CIRCL KEV
May 20, 2026
Added to ENISA EUVD
May 20, 2026
Last updated
Aug 10, 2026
Weakness Type
- CWE-59 Improper Link Resolution Before File Access ('Link Following')
References
FAQ
Common Questions.
Improper link resolution before file access ('link following') in Microsoft Defender allows an authorized attacker to elevate privileges locally.
Affected: Malware Protection Engine (Microsoft) versions >= 1.1.0.0. The full list is in the CVE brief.
It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since May 19, 2026.
Yes. It was added on May 20, 2026 with a federal remediation due date of Jun 3, 2026.
Public exploit code is available.
Fixed versions are available, including Malware Protection Engine 1.1.26040.8.
Brandefense priority: patch immediately, because it is listed as exploited in the wild.
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