How severe is CVE-2021-1721?

CVE-2021-1721 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2021-1721 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (87th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-1721?

CVE-2021-1721 primarily affects Microsoft .net. In total, 6 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-1721?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2021-1721 published?

CVE-2021-1721 was published on 2021-02-25 and last updated on 2026-06-17.

CVE-2021-1721

CVE-2021-1721 is a medium-severity vulnerability in Microsoft .net with a CVSS 3.x base score of 6.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low.

Key facts

Severity: Medium (CVSS 3.x base score 6.5)
CVSS v2: 4.3
EPSS exploit prediction: 3% (87th percentile)
Actively exploited: Not listed in CISA KEV
Affected product: Microsoft .net
Published: 2021-02-25
Last modified: 2026-06-17

Description

.NET Core and Visual Studio Denial of Service Vulnerability

Frequently asked questions

What is CVE-2021-1721?: .NET Core and Visual Studio Denial of Service Vulnerability
How severe is CVE-2021-1721?: CVE-2021-1721 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2021-1721 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (87th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-1721?: CVE-2021-1721 primarily affects Microsoft .net. In total, 6 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-1721?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-1721 published?: CVE-2021-1721 was published on 2021-02-25 and last updated on 2026-06-17.

References

https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-1721

Affected products (6)

cpe:2.3:a:microsoft:.net:*:*:*:*:*:*:*:*
cpe:2.3:a:microsoft:.net_core:*:*:*:*:*:*:*:*
cpe:2.3:a:microsoft:powershell_core:7.0:*:*:*:*:*:*:*
cpe:2.3:a:microsoft:powershell_core:7.1:*:*:*:*:*:*:*
cpe:2.3:a:microsoft:visual_studio_2017:*:*:*:*:*:*:*:*
cpe:2.3:a:microsoft:visual_studio_2019:*:*:*:*:*:*:*:*

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