Review reviewHigh

CVE-2021-26423

Microsoft .NET 5.0, .NET Core 2.1, .NET Core 3.1

CVE-2021-26423 affects Microsoft .NET 5.0, .NET Core 2.1, .NET Core 3.1. Review the CVSS score, exploitation signals, affected versions, remediation status, and linked source material before making a change.

CVSS: 7.5
EPSS: 3.90%
CISA KEV: Not listed
Published: 2021.08.13

PRIORITY ASSESSMENT

Review review

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV

Exploit probability3.90%

Technical severityCVSS 7.5

Vulnerability overview

Affected product and versions

Product: Microsoft .NET 5.0, .NET Core 2.1, .NET Core 3.1
Affected versions: >= 5.0.0 < 5.0.9, >= 2.1 < 2.1.30, >= 3.1 < 3.1.18, >= 15.9.0 < 15.9.38, >= 16.10.0 < 16.10.5, >= 16.0 < 16.4.25, >= 16.0.0 < 16.7.18, >= 15.0.0 < 16.9.10, >= 7.0.0 < 7.0.7, >= 7.1.0 < 7.1.4, >= 8.1.0 < 8.10.7, >= 5.0 <= 5.0.8, >= 2.1 <= 2.1.28, >= 3.1 <= 3.1.17, >= 7.0 < 7.0.7, >= 7.1 < 7.1.4, >= 15.0 <= 15.9, >= 16.0 <= 16.10, 8.10
Fixed versions: 7.0.7, 7.1.4

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide

1
Identify
Confirm that Microsoft .NET 5.0, .NET Core 2.1, .NET Core 3.1 and an affected version are present.
2
Prioritize
Combine exploitation signals with asset exposure and business criticality.
3
Remediate
Follow the vendor advisory or supported update path and preserve rollback options.
4
Verify
Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CWE: Not available