Microsoft · Defender · Microsoft Defender Insufficient Granularity of Access Control Vulnerability
Verdict
Patch on your normal cycle · actively exploited, not reachable unauthenticated from the internet, and in the upper half of CVEs by near-term exploitation probability
Added to CISA KEV 2026-04-22 · exploited in the wild for 158 days · used in ransomware campaigns
CVSS 7.8 HIGH. The score is a summary; these three components are the part that decides whether something scanning the internet can use it.
| Attack vector | localrequires local access to the machine |
|---|---|
| Privileges required | lowneeds some credentials, so a fully anonymous attacker cannot reach it directly |
| User interaction | nonecan be triggered with nobody interacting with the page or request |
| Base vector | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| Weakness | CWE-1220 |
This describes the vulnerability. It says nothing about whether your systems run it.
EPSS puts the probability of exploitation in the next 30 days at 0.0040, which places it in the upper half of all tracked CVEs. The percentile is the more useful half: 0.18 in absolute terms sounds low until you know most of the internet-facing software in the world scores under that.
| EPSS probability | 0.0040 |
|---|---|
| Percentile | 0.315 — upper half |
| Added to KEV | 2026-04-22 |
|---|---|
| Days exploited | 158 |
| Federal remediation due | not set |
| Ransomware use | known to be used in ransomware campaigns |
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Insufficient granularity of access control in Microsoft Defender allows an authorized attacker to elevate privileges locally.