Microsoft Defender Link Following Vulnerability
Microsoft — Microsoft Malware Protection Engine
Improper link resolution before file access ('link following') in Microsoft Defender allows an authorized attacker to elevate privileges locally.
7.8
8.2%
Vector breakdown
- Attack vector
- Local
- Attack complexity
- Low
- Privileges required
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- Published
- May 20, 2026
- Modified
- Jul 24, 2026
- Added to KEV
- May 20, 2026
- Federal patch due
- Jun 3, 2026
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.
Weakness classification
Affected packages
Proof-of-concept & exploitation references
4 foundWeaponization
Public repositories whose name or description references CVE-2026-41091, found via a live GitHub search at request time. These are community-sourced signals, not a verified working exploit - cross-check each one before relying on it, and treat higher star counts and recent activity as (weak) corroboration, not proof.
- 0xBlackash/CVE-2026-41091★ 12
CVE-2026-41091
updated Sep 26, 2026
- tc4dy/CVE-2026-41091-PoC-Exploit★ 4
CVE-2026-41091 RedSun | 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 & Legal uses only.
updated Sep 29, 2026
- s4m98/RedSun-★ 1
Windwos Zero Day Local PrivESc Exploit (CVE-2026-41091)
updated Aug 9, 2026
- ridhinva/defender-privilege-escalation-scanner★ 0
Scanner: CVE-2026-41091/45498 Microsoft Defender LPE/DoS — Python scanner for Windows Defender privilege escalation (CISA KEV)
updated Aug 7, 2026
References
Frequently asked questions
What is CVE-2026-41091?
Improper link resolution before file access ('link following') in Microsoft Defender allows an authorized attacker to elevate privileges locally.
How severe is CVE-2026-41091?
CVE-2026-41091 has a CVSS base score of 7.8 out of 10 (CVSS 3.1).
Is CVE-2026-41091 actively exploited in the wild?
Yes. CVE-2026-41091 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, added May 20, 2026, meaning CISA has confirmed evidence of active exploitation.
What is the EPSS score for CVE-2026-41091?
8.2% - meaning FIRST.org's EPSS model estimates a 8.2% probability this vulnerability will be exploited in the wild within 30 days (94% percentile among all scored CVEs).
Is there exploit tooling available for CVE-2026-41091?
We found 4 public GitHub repositories referencing CVE-2026-41091, though none matched a known Nuclei template or Metasploit module at last check. Review each one before relying on it - see the proof-of-concept section above.
What type of vulnerability is CVE-2026-41091?
CVE-2026-41091 is classified under CWE-59 (CWE-59: Improper Link Resolution Before File Access ('Link Following')).
Cross-checked against
Impactr finds and proves whether CVE-2026-41091 - or flaws like it - are actually reachable in your own web apps and APIs, with a reproducible exploit as evidence.
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