How severe is CVE-2021-43877?

CVE-2021-43877 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-43877 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (49th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-43877?

CVE-2021-43877 primarily affects Microsoft Asp.net Core. In total, 7 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-43877?

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-2021-43877 published?

CVE-2021-43877 was published on 2021-12-15 and last updated on 2026-06-17.

CVE-2021-43877

CVE-2021-43877 is a high-severity vulnerability in Microsoft Asp.net Core with a CVSS 3.x base score of 8.8. 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 8.8)
CVSS v2: 4.6
EPSS exploit prediction: 1% (49th percentile)
Actively exploited: Not listed in CISA KEV
Affected product: Microsoft Asp.net Core
Published: 2021-12-15
Last modified: 2026-06-17

Description

ASP.NET Core and Visual Studio Elevation of Privilege Vulnerability

Frequently asked questions

What is CVE-2021-43877?: ASP.NET Core and Visual Studio Elevation of Privilege Vulnerability
How severe is CVE-2021-43877?: CVE-2021-43877 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-43877 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (49th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-43877?: CVE-2021-43877 primarily affects Microsoft Asp.net Core. In total, 7 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-43877?: 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-2021-43877 published?: CVE-2021-43877 was published on 2021-12-15 and last updated on 2026-06-17.

References

https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-43877

Affected products (7)

cpe:2.3:a:microsoft:asp.net_core:3.1:*:*:*:*:*:*:*
cpe:2.3:a:microsoft:asp.net_core:5.0:*:*:*:*:*:*:*
cpe:2.3:a:microsoft:asp.net_core:6.0:*:*:*:*:*:*:*
cpe:2.3:a:microsoft:visual_studio_2019:16.7:*:*:*:*:*:*:*
cpe:2.3:a:microsoft:visual_studio_2019:16.9:*:*:*:*:*:*:*
cpe:2.3:a:microsoft:visual_studio_2019:16.11:*:*:*:*:*:*:*
cpe:2.3:a:microsoft:visual_studio_2022:17.0:*:*:*:*:*:*:*

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