CVE-2021-34532: ASP.NET Core Information Disclosure Vulnerability

August 25, 2021 (updated August 11, 2026)

Microsoft is releasing this security advisory to provide information about a vulnerability in .NET 5.0, .NET Core 3.1 and .NET Core 2.1. This advisory also provides guidance on what developers can do to update their applications to remove this vulnerability.

An information disclosure vulnerability exists in .NET 5.0, .NET Core 3.1 and .NET Core 2.1 where a JWT token is logged if it cannot be parsed.

References

github.com/advisories/GHSA-q7cg-43mg-qp69
github.com/dotnet/aspnetcore/security/advisories/GHSA-q7cg-43mg-qp69
msrc.microsoft.com/update-guide/vulnerability/CVE-2021-34532
nvd.nist.gov/vuln/detail/CVE-2021-34532
portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-34532

Code Behaviors & Features

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