CVE-2026-33825
Microsoft Defender · Security products
Microsoft Defender Insufficient Granularity of Access Control Vulnerability
At a glance
Exploited. Added to CISA’s catalog of exploited vulnerabilities on April 22, 2026.
Used in ransomware attacks, according to CISA.
Affected product: Microsoft Defender (category Security products, indicative classification). Name in CISA’s catalog: Microsoft Defender.
Microsoft component: Microsoft Defender (Security and compliance products).
What should I do?
Apply the patches or mitigations from Microsoft; if none are available, stop using the product. For cloud services, follow the guidance from Microsoft.
Deadline set by CISA for US federal agencies: 14 days (due May 6, 2026). It only binds those agencies, but it is a useful measure of urgency.
- CVE-2026-33825 in Microsoft’s Security Update Guide
- Microsoft security advisories page (general page, not the advisory for this vulnerability)
- The vendor’s specific advisory is listed in the NVD references: CVE-2026-33825 on the NVD website.
Original text of the required action (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.
Timeline
- Vulnerability published Publication date (NVD)
- Exploitation confirmed Added to CISA’s KEV catalog
- CISA deadline Remediation deadline set for US federal agencies
The facts, with their sources
- Exploitation confirmed
- Yes, on April 22, 2026 Date added to the catalog of exploited vulnerabilities. Exploitation itself may have started earlier. Source: KEV catalog, collected September 29, 2026 at 14:57 UTC
- Ransomware
- Known use Source: KEV catalog, collected September 29, 2026 at 14:57 UTC
- Hunt for compromise
- Not requested by CISA Source: KEV catalog, collected September 29, 2026 at 14:57 UTC
- CISA required action
- Apply the patches or mitigations from Microsoft; if none are available, stop using the product. For cloud services, follow the guidance from Microsoft. Rewritten by this site from CISA’s original text. Source: KEV catalog, collected September 29, 2026 at 14:57 UTC
- CISA deadline
- May 6, 2026, 14 days Set for US federal agencies: a measure of urgency, not an obligation elsewhere. Source: KEV catalog, collected September 29, 2026 at 14:57 UTC
- Microsoft patch
- Not available Source: Security Update Guide, collected September 29, 2026 at 14:57 UTC
- Vulnerability published
- April 14, 2026 Source: National Vulnerability Database (NVD), collected September 29, 2026 at 15:00 UTC
- Product according to CISA
- Microsoft Defender Filed by this site under “Security products” (indicative classification). Source: KEV catalog, collected September 29, 2026 at 14:57 UTC
- CVSS vector
- CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H Technical detail of the score: attack vector, complexity, impact. Source: National Vulnerability Database (NVD), collected September 29, 2026 at 15:00 UTC
Severity and activity
Score from the vendor or CISA, relayed by the NVD. Collected Sep 29, 2026.
FIRST’s EPSS model. Since exploitation is already confirmed, this figure is mostly useful to compare activity. Collected Sep 29, 2026.
Description
Insufficient granularity of access control in Microsoft Defender allows an authorized attacker to elevate privileges locally.
Official description from the NVD, collected Sep 29, 2026. CVE® description © The MITRE Corporation.
Microsoft Defender contains an insufficient granularity of access control vulnerability that could allow an authorized attacker to escalate privileges locally.
Summary from CISA (KEV catalog).
CERT-FR advisories
No advisory among the latest CERT-FR publications this site follows. That does not mean there are none.
Information reused under the Open Licence 2.0 (Etalab); the date of last update is shown for each advisory. This site is neither affiliated with nor endorsed by ANSSI.
Sources for this page
- CISA KEV catalog: exploitation, date added, required action, deadline, ransomware.
- Microsoft Security Update Guide: product, patch.
- NVD (NIST): CVSS severity, publication date, description, vendor references.
- EPSS (FIRST): probability of exploitation.
- CERT-FR: advisories and alerts (in French).
- Brand and category: indicative classification by this site (method).