CVE-2026-41091
Microsoft Defender Link Following Vulnerability
Does this matter?
Known to be exploited in the wild (CISA KEV, CISA remediation deadline 3 June 2026). Treat as an emergency change: patch or isolate now, then hunt for prior compromise.
Description
Improper link resolution before file access ('link following') in Microsoft Defender allows an authorized attacker to elevate privileges locally.
- CVSS 3.1
- 7.8 HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- EPSS
- 8.20% probability · 95th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Listed 20 May 2026 · due 3 June 2026
- Weakness
- CWE-59
- Affected
- microsoft/malware protection engine
- Source
- secure@microsoft.com
EPSS moved from 0.4% on 24 September 2026 to 8.2% on 27 October 2026. The dashed line is the ten per cent mark our analysts treat as “patch before the next change window”.
CISA notes
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable. https://msrc.microsoft.com/update-guide/en-US/vulnerability/CVE-2026-41091 ; https://nvd.nist.gov/vuln/detail/CVE-2026-41091
References
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-41091Vendor Advisory
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-41091Third Party Advisory, US Government Resource
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.