VulnerabilityAnalyzed

CVE-2026-41091

Microsoft Defender Link Following Vulnerability

KEVHIGH 7.8EPSS 8.20%

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
CISA KEV: Listed 20 May 2026 · due 3 June 2026
Weakness: CWE-59
Affected: microsoft/malware protection engine
Source: secure@microsoft.com

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. Refreshed daily.