How severe is CVE-2021-34532?

CVE-2021-34532 has a CVSS score of 5.5 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.

Which versions of Microsoft.AspNetCore.Authentication.JwtBearer are affected by CVE-2021-34532?

Microsoft.AspNetCore.Authentication.JwtBearer (nuget) versions >= 3.0.0, < 3.1.18 is affected.

Is there a fix for CVE-2021-34532?

Yes. CVE-2021-34532 is fixed in 3.1.18, 5.0.9, 2.1.29. Upgrade to this version or later.

Is CVE-2021-34532 exploitable, and should I be worried?

Whether CVE-2021-34532 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk.

What actually determines whether CVE-2021-34532 is exploitable, and how bad it is?

Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.

How do I fix CVE-2021-34532?

Upgrade: Microsoft.AspNetCore.Authentication.JwtBearer to 3.1.18 or later, Microsoft.AspNetCore.Authentication.JwtBearer to 5.0.9 or later, Microsoft.AspNetCore.Authentication.JwtBearer to 2.1.29 or later.

CVE-2021-34532

Q: What is CVE-2021-34532?

CVE-2021-34532 is a medium-severity security vulnerability in Microsoft.AspNetCore.Authentication.JwtBearer (nuget), affecting versions >= 3.0.0, < 3.1.18. It is fixed in 3.1.18, 5.0.9, 2.1.29.

Q: Is there a fix for CVE-2021-34532?

Yes. CVE-2021-34532 is fixed in 3.1.18, 5.0.9, 2.1.29. Upgrade to this version or later.

Q: Is CVE-2021-34532 exploitable, and should I be worried?

Whether CVE-2021-34532 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk.

Q: What actually determines whether CVE-2021-34532 is exploitable, and how bad it is?

Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.

Q: How do I fix CVE-2021-34532?

Upgrade: Microsoft.AspNetCore.Authentication.JwtBearer to 3.1.18 or later, Microsoft.AspNetCore.Authentication.JwtBearer to 5.0.9 or later, Microsoft.AspNetCore.Authentication.JwtBearer to 2.1.29 or later.

Summary

ASP.NET Core Information Disclosure Vulnerability

Impact

CVE-2021-34532 has a CVSS score of 5.5 (Medium). The vector is requires local access, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (3.1.18, 5.0.9, 2.1.29); upgrading removes the vulnerable code path.

Affected versions

Microsoft.AspNetCore.Authentication.JwtBearer (>= 3.0.0, < 3.1.18) Microsoft.AspNetCore.Authentication.JwtBearer (>= 5.0.0, < 5.0.9) Microsoft.AspNetCore.Authentication.JwtBearer (>= 2.1.0, < 2.1.29)

Security releases

Microsoft.AspNetCore.Authentication.JwtBearer → 3.1.18 (nuget) Microsoft.AspNetCore.Authentication.JwtBearer → 5.0.9 (nuget) Microsoft.AspNetCore.Authentication.JwtBearer → 2.1.29 (nuget)

Kodem intelligence

Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.

Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.

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Remediation advice

If you're using .NET 5.0, you should download and install Runtime 5.0.9 or SDK 5.0.206 (for Visual Studio 2019 v16.8) or SDK 5.0.303 (for Visual Studio 2019 V16.10) from https://dotnet.microsoft.com/download/dotnet-core/5.0.
If you're using .NET Core 3.1, you should download and install Runtime 3.1.18 or SDK 3.1.118 (for Visual Studio 2019 v16.4) or 3.1.412 (for Visual Studio 2019 v16.7 or later) from https://dotnet.microsoft.com/download/dotnet-core/3.1.
If you're using .NET Core 2.1, you should download and install Runtime 2.1.29 or SDK 2.1.525 (for Visual Studio 2019 v15.9) or 2.1.817 from https://dotnet.microsoft.com/download/dotnet-core/2.1.
If your application is using .NET Core 2.1 running on .NET Framework see the Updating .NET Core 2.1 on .NET Framework section below.

Frequently Asked Questions

What is CVE-2021-34532? CVE-2021-34532 is a medium-severity security vulnerability in Microsoft.AspNetCore.Authentication.JwtBearer (nuget), affecting versions >= 3.0.0, < 3.1.18. It is fixed in 3.1.18, 5.0.9, 2.1.29.
How severe is CVE-2021-34532? CVE-2021-34532 has a CVSS score of 5.5 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
Which versions of Microsoft.AspNetCore.Authentication.JwtBearer are affected by CVE-2021-34532? Microsoft.AspNetCore.Authentication.JwtBearer (nuget) versions >= 3.0.0, < 3.1.18 is affected.
Is there a fix for CVE-2021-34532? Yes. CVE-2021-34532 is fixed in 3.1.18, 5.0.9, 2.1.29. Upgrade to this version or later.
Is CVE-2021-34532 exploitable, and should I be worried? Whether CVE-2021-34532 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
What actually determines whether CVE-2021-34532 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
How do I fix CVE-2021-34532?
- Upgrade Microsoft.AspNetCore.Authentication.JwtBearer to 3.1.18 or later
- Upgrade Microsoft.AspNetCore.Authentication.JwtBearer to 5.0.9 or later
- Upgrade Microsoft.AspNetCore.Authentication.JwtBearer to 2.1.29 or later