Exploited vulnerability · CISA KEV

Is CVE-2026-33825 exploited? Yes: in CISA KEV since 22 Apr 2026

Gociux · Microsoft Defender · data: CISA KEV, CVE record, FIRST EPSS

Yes. CVE-2026-33825, Microsoft Defender Insufficient Granularity of Access Control Vulnerability, is being exploited in the wild. CISA added it to its Known Exploited Vulnerabilities catalog on 22 Apr 2026, 8 days after it was published. It is known to be used in ransomware campaigns. It affects Microsoft Defender. If you run it, CISA's required action is: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

What it is

Microsoft Defender contains an insufficient granularity of access control vulnerability that could allow an authorized attacker to escalate privileges locally.

What to do

1. Check whether you run it. Look for Defender in your asset inventory, including appliances and cloud images. Stack check lists every exploited Microsoft CVE at once.
2. Apply the fix. Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
3. If you can't patch today, take the affected service off the internet or restrict who can reach it, and check its logs for signs of compromise since 14 Apr 2026.
4. Get told next time. Email alerts when CISA adds a CVE for Microsoft.

Other exploited CVEs in Defender

• CVE-2026-41091: Microsoft Defender Link Following Vulnerability (20 May 2026)
• CVE-2026-45498: Microsoft Defender Denial of Service Vulnerability (20 May 2026)
• CVE-2022-44698: Microsoft Defender SmartScreen Security Feature Bypass Vulnerability (13 Dec 2022)
• CVE-2021-1647: Microsoft Defender Remote Code Execution Vulnerability (3 Nov 2021)

References

• msrc.microsoft.com/update-guide/vulnerability/CVE-2026-33825
• nvd.nist.gov/vuln/detail/CVE-2026-33825

Sources: CISA KEV (exploitation, ransomware use, required action, due date), the CVE record (publication date, CVSS, CNA), NVD and FIRST EPSS (live score). More: all KEV additions in April 2026 · Microsoft scorecard · act-now radar.