How severe is CVE-2023-21809?

CVE-2023-21809 has a CVSS 3.x base score of 7.8, rated high severity. It is exploitable over local access with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2023-21809 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (44th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2023-21809?

CVE-2023-21809 affects Microsoft Defender Security Intelligence Updates. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2023-21809?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2023-21809 published?

CVE-2023-21809 was published on 2023-02-14 and last updated on 2026-06-17.

CVE-2023-21809

CVE-2023-21809 is a high-severity vulnerability in Microsoft Defender Security Intelligence Updates with a CVSS 3.x base score of 7.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low.

Key facts

Severity: High (CVSS 3.x base score 7.8)
EPSS exploit prediction: 1% (44th percentile)
Actively exploited: Not listed in CISA KEV
Affected product: Microsoft Defender Security Intelligence Updates
Published: 2023-02-14
Last modified: 2026-06-17

Description

Microsoft Defender for Endpoint Security Feature Bypass Vulnerability

Frequently asked questions

What is CVE-2023-21809?: Microsoft Defender for Endpoint Security Feature Bypass Vulnerability
How severe is CVE-2023-21809?: CVE-2023-21809 has a CVSS 3.x base score of 7.8, rated high severity. It is exploitable over local access with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2023-21809 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (44th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2023-21809?: CVE-2023-21809 affects Microsoft Defender Security Intelligence Updates. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2023-21809?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2023-21809 published?: CVE-2023-21809 was published on 2023-02-14 and last updated on 2026-06-17.

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2023-21809

Affected products (1)

cpe:2.3:a:microsoft:defender_security_intelligence_updates:*:*:*:*:*:*:*:*