CVE-2026-41091: Microsoft Defender Elevation of Privilege Vulnerability
Noroxi assessment
Priority: This week (action score 63/100)
- CISA has confirmed exploitation in the wild (May 20, 2026). Remediation deadline for US federal agencies: Jun 3, 2026.
- Probability of exploitation in the next 30 days: 8.2% (FIRST EPSS); higher than 94.9% of all records.
- Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
- Fixed version: Microsoft Malware Protection Engine 1.1.26040.8.
Don’t wait for the next maintenance window. Upgrade to Microsoft Malware Protection Engine 1.1.26040.8 or later.
Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it
Primary sources: NVD · CVE.org · CISA KEV · FIRST EPSS
Improper link resolution before file access ('link following') in Microsoft Defender allows an authorized attacker to elevate privileges locally.
- Published
- May 20, 2026
- Updated
- Aug 10, 2026
- EPSS
- 8.2% · 94th percentile
- CWE
- CWE-59
Report tools
Action score
63
Don’t wait for the next maintenance window.
- CVSS
- 31 / 40 · 7.8 / 10
- CISA KEV
- 30 / 30 · Listed
- EPSS
- 2 / 30 · 8.2%
CISA SSVC decision
- Exploitation
- active
- Automatable
- no
- Technical impact
- total
Vulnrichment: CISA's decision-tree inputs.
CNA vs NVD score
- NVD
- —
- CNA · microsoft
- 7.8
- NVD has not scored this yet; the score shown is the CNA’s.
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.
Actively exploited in the wild
CISA added this to its Known Exploited Vulnerabilities catalog on May 20, 2026. That signals real attacks, not theory.
Remediation deadline for US federal agencies: Jun 3, 2026.
Get told when this record changes
- In CISA KEV: exploitation in the wild confirmed
- Weaponized exploit exists
- A fix has been released
If any of these changes, we'll tell you in the daily email digest.
Is your version affected? Check itNoroxi analysis
What does it mean in your environment?
The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.
We use this product, ask for helpAffected systems
Is your version affected?
Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.
| Vendor | Product | CPE |
|---|---|---|
| microsoft | malware protection engine | cpe:2.3:a:microsoft:malware_protection_engine |
Versions reported by the vendor
Affected version ranges reported by the assigning authority (microsoft). Independent of NVD's CPE analysis and usually ahead of it.
Microsoft Microsoft Malware Protection Engine
- 1.1.0.0 and later · before 1.1.26040.8affected
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- microsoft malware protection engine1.1.26030.3008 and later · before 1.1.26040.8
Same product
microsoft: all recordsOther highest-scoring records for the same primary product.
- CVE-2017-8540The Microsoft Malware Protection Engine running on Microsoft Forefront and Microsoft Defender on Microsoft Windows Server 2008 SP2 and R2…KEV83Now
- CVE-2013-1346mpengine.dll in Microsoft Malware Protection Engine before 1.1.9506.0 on x64 platforms allows remote attackers to execute arbitrary code or…40Plan
- CVE-2017-11937The Microsoft Malware Protection Engine running on Microsoft Forefront and Microsoft Defender on Windows 7 SP1, Windows 8.1, Windows RT…39Monitor
Published before and after this one in the same product
- ← EarlierCVE-2023-24860Apr 11, 2023 · Microsoft Defender Denial of Service Vulnerability31Monitor
- ← EarlierCVE-2023-33156Jul 11, 2023 · Microsoft Defender Elevation of Privilege Vulnerability28Monitor
- Later →CVE-2026-45584May 20, 2026 · Microsoft Defender Remote Code Execution Vulnerability32Monitor
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| Microsoft Malware Protection Engine | 1.1.26040.8 · Release Notes | Microsoft (MSRC) |
Exploit status
Weaponized
A ready exploit tool or active in-the-wild use is known for this vulnerability. This should be your top priority.
Evidence
- Proof-of-concept repository on GitHub ×4
Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.
| Source | Kind | Date |
|---|---|---|
| Proof-of-concept repository on GitHub | 4 repositories | 2026-05-21 → 2026-08-09 |
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
- CISA KEVsame day
- Published
- First PoC+1 d
- TodayNov 14, 2026+178 d
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
- CVE-2026-5065627 days apartMicrosoft Defender Elevation of Privilege Vulnerability31Monitor
- CVE-2026-6941486 days apartMicrosoft Defender Elevation of Privilege Vulnerability31Monitor
Not on record for this CVE: patch commit or PR link · researcher credit · public bounty program.
Technical details
Attack conditions
- Someone with local access to the system can trigger it.
- A low-privileged account is enough.
- No user action is required.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- high · data can be read
- Integrity
- high · data or configuration can be modified
- Availability
- high · the service can be disrupted
- Attack vector
- Local
- Attack complexity
- Low
- Privileges required
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- High
- Integrity impact
- High
- Availability impact
- High
Weakness class (CWE)
CWE-59 · Improper Link Resolution Before File Access ('Link Following')CVSS vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
nvd-secondary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
Attack patterns (CAPEC)
ATT&CK techniques
- Obfuscated Files or Information: HTML SmugglingT1027.006
- Obfuscated Files or Information: Embedded PayloadsT1027.009
- Boot or Logon Autostart Execution:Shortcut ModificationT1547.009
- Hide Artifacts: Resource ForkingT1564.009
- Hijack Execution Flow: Executable Installer File Permissions WeaknessT1574.005
- Hijack Execution Flow: Services File Permissions WeaknessT1574.010
Change log (1)
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
Show all references (1 more)Show less
Vendor advisories and official records. Exploit/PoC links are deliberately left out.