CVE-2026-41091: in the CISA KEV catalogue

Microsoft Defender Link Following Vulnerability. CISA added CVE-2026-41091 to the Known Exploited Vulnerabilities catalogue on 2026-05-20 with a default due date of 2026-06-03. Known ransomware campaign use: Unknown. Forensic triage flag: No.

Microsoft Defender contains a link following vulnerability that allows an authorized attacker to elevate privileges locally. (CISA description)

Vendor / product: Microsoft Defender
CWE: CWE-59
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.
EPSS: 8.2%, percentile 94 (scored 2026-11-03)

EPSS puts about 8.2 in 100 odds (8.2%) on exploitation activity being observed in the next 30 days. Its score is higher than or equal to that of 94% of scored CVEs. This is a model estimate about exploitation anywhere, not about your environment.

Vendor and reference links (from CISA)

Your own deadline under CISA BOD 26-04 depends on exposure, automatability and technical impact: work it out with the BOD 26-04 calculator.

Data dates. CISA KEV catalogue version 2026.11.03, released 2026-11-03, 1,767 entries (checked 2026-11-03). EPSS model v2026.06.15, scored 2026-11-03, 399,388 CVEs. Sources: CISA and FIRST (EPSS by FIRST; scores generated by Empirical Security). Copied to our own database and refreshed automatically; if a refresh fails, the previous copy keeps serving with its own date.

Frequently asked questions

Is CVE-2026-41091 in the CISA KEV catalogue?

Yes. CISA added CVE-2026-41091 (Microsoft Defender Link Following Vulnerability) to the Known Exploited Vulnerabilities catalogue on 2026-05-20. CISA's default due date for it is 2026-06-03.

Is CVE-2026-41091 used in ransomware attacks?

CISA marks known ransomware campaign use as Unknown for CVE-2026-41091. That means CISA lacks confirmation, not that ransomware groups do not use it.

What should I do about CVE-2026-41091?

CISA's 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.

Sources

CISA, Known Exploited Vulnerabilities Catalog (accessed 2026-11-03)
FIRST, Exploit Prediction Scoring System (EPSS) (EPSS by FIRST; scores generated by Empirical Security)
NVD record for CVE-2026-41091