CVE-2025-55315

Inconsistent interpretation of http requests ('http request/response smuggling') in ASP.NET Core allows an authorized attacker to bypass a security feature over a network.

Microsoft Security Advisory CVE-2025-55315: .NET Security Feature Bypass Vulnerability

<a name="executive-summary"></a>Executive summary

Microsoft is releasing this security advisory to provide information about a vulnerability in ASP.NET Core 10.0 , ASP.NET Core 9.0 , ASP.NET Core 8.0, and ASP.NET Core 2.3. This advisory also provides guidance on what developers can do to update their applications to address this vulnerability.

Inconsistent interpretation of http requests ('http request/response smuggling') in ASP.NET Core allows an authorized attacker to bypass a security feature over a network.

Discussion

Discussion for this issue can be found at https://github.com/dotnet/announcements/issues/371

<a name="mitigation-factors"></a>Mitigation factors

Microsoft has not identified any mitigating factors for this vulnerability.

<a name="affected-software"></a>Affected software

• Any ASP.NET Core 10.0 application running on ASP.NET Core 10.0.0-rc.1.25451.107 or earlier.
• Any ASP.NET Core 9.0 application running on ASP.NET Core 9.0.9 or earlier.
• Any ASP.NET Core application running on ASP.NET Core 8.0.20 or earlier.
• Any ASP.NET Core 2.x application consuming the package Microsoft.AspNetCore.Server.Kestrel.Core version 2.3.0 or earlier.

<a name="affected-packages"></a>Affected Packages

The vulnerability affects any Microsoft .NET Core project if it uses any of affected packages versions listed below

Package name | Affected version | Patched version ------------ | ---------------- | ------------------------- Microsoft.AspNetCore.Server.Kestrel.Core | <= 2.3.0 | 2.3.6

<a name="ASP.NET Core 10"></a>ASP.NET Core 10

Package name | Affected version | Patched version ------------ | ---------------- | ------------------------- Microsoft.AspNetCore.App.Runtime.linux-arm | 10.0.0-rc.1.25451.107 | 10.0.0-rc.2.25502.107 Microsoft.AspNetCore.App.Runtime.linux-arm64 | 10.0.0-rc.1.25451.107 | 10.0.0-rc.2.25502.107 Microsoft.AspNetCore.App.Runtime.linux-musl-arm | 10.0.0-rc.1.25451.107 | 10.0.0-rc.2.25502.107 Microsoft.AspNetCore.App.Runtime.linux-musl-arm64 | 10.0.0-rc.1.25451.107 | 10.0.0-rc.2.25502.107 Microsoft.AspNetCore.App.Runtime.linux-musl-x64 | 10.0.0-rc.1.25451.107 | 10.0.0-rc.2.25502.107 Microsoft.AspNetCore.App.Runtime.linux-x64 | 10.0.0-rc.1.25451.107 | 10.0.0-rc.2.25502.107 Microsoft.AspNetCore.App.Runtime.osx-arm64 | 10.0.0-rc.1.25451.107 | 10.0.0-rc.2.25502.107 Microsoft.AspNetCore.App.Runtime.osx-x64 | 10.0.0-rc.1.25451.107 | 10.0.0-rc.2.25502.107 Microsoft.AspNetCore.App.Runtime.win-arm | 10.0.0-rc.1.25451.107 | 10.0.0-rc.2.25502.107 Microsoft.AspNetCore.App.Runtime.win-arm64 | 10.0.0-rc.1.25451.107 | 10.0.0-rc.2.25502.107 Microsoft.AspNetCore.App.Runtime.win-x64 | 10.0.0-rc.1.25451.107 | 10.0.0-rc.2.25502.107 Microsoft.AspNetCore.App.Runtime.win-x86 |…

.NET is a managed-software framework. It implements a subset of the .NET framework APIs and several new APIs, and it includes a CLR implementation.

New versions of .NET that address a security vulnerability are now available. The updated versions are .NET SDK 8.0.121 and .NET Runtime 8.0.21.Security Fix(es):

• dotnet: .NET Information Disclosure Vulnerability (CVE-2025-55248)

• dotnet: .NET Security Feature Bypass Vulnerability (CVE-2025-55315)

• dotnet: .NET Denial of Service Vulnerability (CVE-2025-55247)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

.NET is a managed-software framework. It implements a subset of the .NET framework APIs and several new APIs, and it includes a CLR implementation.

New versions of .NET that address a security vulnerability are now available. The updated versions are .NET SDK 8.0.121 and .NET Runtime 8.0.21.Security Fix(es):

• dotnet: .NET Information Disclosure Vulnerability (CVE-2025-55248)

• dotnet: .NET Security Feature Bypass Vulnerability (CVE-2025-55315)

• dotnet: .NET Denial of Service Vulnerability (CVE-2025-55247)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

.NET is a managed-software framework. It implements a subset of the .NET framework APIs and several new APIs, and it includes a CLR implementation.

New versions of .NET that address a security vulnerability are now available. The updated versions are .NET SDK 9.0.111 and .NET Runtime 9.0.10.Security Fix(es):

• dotnet: .NET Information Disclosure Vulnerability (CVE-2025-55248)

• dotnet: .NET Security Feature Bypass Vulnerability (CVE-2025-55315)

• dotnet: .NET Denial of Service Vulnerability (CVE-2025-55247)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

.NET is a managed-software framework. It implements a subset of the .NET framework APIs and several new APIs, and it includes a CLR implementation.

New versions of .NET that address a security vulnerability are now available. The updated versions are .NET SDK 9.0.111 and .NET Runtime 9.0.10.Security Fix(es):

• dotnet: .NET Information Disclosure Vulnerability (CVE-2025-55248)

• dotnet: .NET Security Feature Bypass Vulnerability (CVE-2025-55315)

• dotnet: .NET Denial of Service Vulnerability (CVE-2025-55247)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

.NET is a managed-software framework. It implements a subset of the .NET framework APIs and several new APIs, and it includes a CLR implementation.

New versions of .NET that address a security vulnerability are now available. The updated versions are .NET SDK 8.0.121 and .NET Runtime 8.0.21.Security Fix(es):

• dotnet: .NET Information Disclosure Vulnerability (CVE-2025-55248)

• dotnet: .NET Security Feature Bypass Vulnerability (CVE-2025-55315)

• dotnet: .NET Denial of Service Vulnerability (CVE-2025-55247)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

.NET is a managed-software framework. It implements a subset of the .NET framework APIs and several new APIs, and it includes a CLR implementation.

New versions of .NET that address a security vulnerability are now available. The updated versions are .NET SDK 9.0.111 and .NET Runtime 9.0.10.Security Fix(es):

• dotnet: .NET Information Disclosure Vulnerability (CVE-2025-55248)

• dotnet: .NET Security Feature Bypass Vulnerability (CVE-2025-55315)

• dotnet: .NET Denial of Service Vulnerability (CVE-2025-55247)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Inconsistent interpretation of http requests ('http request/response smuggling') in ASP.NET Core allows an authorized attacker to bypass a security feature over a network.

.NET is a managed-software framework. It implements a subset of the .NET framework APIs and several new APIs, and it includes a CLR implementation.

New versions of .NET that address a security vulnerability are now available. The updated versions are .NET SDK 8.0.121 and .NET Runtime 8.0.21.Security Fix(es):

• dotnet: .NET Information Disclosure Vulnerability (CVE-2025-55248)
• dotnet: .NET Security Feature Bypass Vulnerability (CVE-2025-55315)
• dotnet: .NET Denial of Service Vulnerability (CVE-2025-55247)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

.NET is a managed-software framework. It implements a subset of the .NET framework APIs and several new APIs, and it includes a CLR implementation.

New versions of .NET that address a security vulnerability are now available. The updated versions are .NET SDK 8.0.121 and .NET Runtime 8.0.21.Security Fix(es):

• dotnet: .NET Information Disclosure Vulnerability (CVE-2025-55248)
• dotnet: .NET Security Feature Bypass Vulnerability (CVE-2025-55315)
• dotnet: .NET Denial of Service Vulnerability (CVE-2025-55247)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

.NET is a managed-software framework. It implements a subset of the .NET framework APIs and several new APIs, and it includes a CLR implementation.

New versions of .NET that address a security vulnerability are now available. The updated versions are .NET SDK 9.0.111 and .NET Runtime 9.0.10.Security Fix(es):

• dotnet: .NET Information Disclosure Vulnerability (CVE-2025-55248)
• dotnet: .NET Security Feature Bypass Vulnerability (CVE-2025-55315)
• dotnet: .NET Denial of Service Vulnerability (CVE-2025-55247)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

.NET is a managed-software framework. It implements a subset of the .NET framework APIs and several new APIs, and it includes a CLR implementation.

New versions of .NET that address a security vulnerability are now available. The updated versions are .NET SDK 9.0.111 and .NET Runtime 9.0.10.Security Fix(es):

• dotnet: .NET Information Disclosure Vulnerability (CVE-2025-55248)
• dotnet: .NET Security Feature Bypass Vulnerability (CVE-2025-55315)
• dotnet: .NET Denial of Service Vulnerability (CVE-2025-55247)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

.NET is a managed-software framework. It implements a subset of the .NET framework APIs and several new APIs, and it includes a CLR implementation.

New versions of .NET that address a security vulnerability are now available. The updated versions are .NET SDK 8.0.121 and .NET Runtime 8.0.21.Security Fix(es):

• dotnet: .NET Information Disclosure Vulnerability (CVE-2025-55248)
• dotnet: .NET Security Feature Bypass Vulnerability (CVE-2025-55315)
• dotnet: .NET Denial of Service Vulnerability (CVE-2025-55247)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

.NET is a managed-software framework. It implements a subset of the .NET framework APIs and several new APIs, and it includes a CLR implementation.

New versions of .NET that address a security vulnerability are now available. The updated versions are .NET SDK 9.0.111 and .NET Runtime 9.0.10.Security Fix(es):

• dotnet: .NET Information Disclosure Vulnerability (CVE-2025-55248)
• dotnet: .NET Security Feature Bypass Vulnerability (CVE-2025-55315)
• dotnet: .NET Denial of Service Vulnerability (CVE-2025-55247)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Inconsistent interpretation of http requests ('http request/response smuggling') in ASP.NET Core allows an authorized attacker to bypass a security feature over a network.

It was discovered that .NET did not properly handle the creation of temporary build time directories. An attacker could possibly use this issue to cause a denial of service. (CVE-2025-55247)

It was discovered that .NET did not properly establish TLS sessions for SMTP server connections. An attacker could use this issue to cause .NET to use unencrypted connections. This issue only affects .NET versions 8.0 and 9.0. (CVE-2025-55248)

It was discovered that .NET inconsistently interpreted certain http requests. An attacker could possibly use this to bypass a security feature over a network. (CVE-2025-55315)