CVE-2026-41091: Microsoft Defender Link Following Vulnerability
- Is it exploited?
Yes. CISA added it to the Known Exploited Vulnerabilities catalog on 20 May 2026, the same day the CVE record was published.
- How likely is exploitation in the next 30 days?
- 8.2%
EPSS score, percentile 94.9 of all scored records
- How severe?
- 7.8 High
CVSS v3.1 base score, given by the CNA
- What should I do?
CISA deadline 3 Jun 2026. Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
- Which versions are affected?
Affected
- from 1.1.0.0 to before 1.1.26040.8
Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.
What to do
Required action, set by CISA
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
CISA due date for this action: 3 June 2026.
Advisories and patches
Linked from CISA's catalog entry
- https://msrc.microsoft.com/update-guide/en-US/vulnerability/CVE-2026-41091
- https://nvd.nist.gov/vuln/detail/CVE-2026-41091
Affected products and versions
As listed in the CVE record.
| Status | Versions |
|---|---|
| Affected | from 1.1.0.0 to before 1.1.26040.8 |
Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.
About this vulnerability
Microsoft Defender contains a link following vulnerability that allows an authorized attacker to elevate privileges locally.
Summary: CISA's KEV catalog, as of 28 Oct 2026.
- CISA added CVE-2026-41091 to its Known Exploited Vulnerabilities (KEV) catalog on 20 May 2026.
- CISA's ransomware flag for this entry is "Unknown": no evidence of ransomware use in the catalog, which is not proof of none.
- The due date CISA sets for the required action is 3 Jun 2026.
- The CVE record was published on 20 May 2026, the same day it was added to KEV.
- The CVE record carries a CVSS v3.1 base score of 7.8 (High), given by its CNA.
- FIRST's EPSS model puts the probability of exploitation in the next 30 days at 8.2% (percentile 94.9), as of 28 Oct 2026.
- CISA's SSVC assessment in the CVE record: exploitation active, automatable no, technical impact total.
Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026. About the data.
Description
Microsoft Defender Elevation of Privilege Vulnerability
Improper link resolution before file access ('link following') in Microsoft Defender allows an authorized attacker to elevate privileges locally.
Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.
Weakness
- CWE-59: Improper Link Resolution Before File Access ('Link Following')
CWE and CAPEC are maintained by MITRE; the entries are those named in the CVE record and the KEV entry.
Timeline
| Date | Event |
|---|---|
| 20 May 2026 | CVE record published |
| 20 May 2026 | Added to CISA KEV |
| 3 Jun 2026 | CISA due date for the required action |
| 10 Aug 2026 | CVE record last updated |
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