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CVE-2026-96958BIT-dotnet-2026-96958BIT-dotnet-sdk-2026-96958GHSA-r955-8q5j-3h83

System.Security.Cryptography.Xml: Microsoft Security Advisory CVE-2026-96958 - .NET and Visual Studio Denial of Service Vulnerability

Microsoft System.Security.Cryptography.XmlnugetLibraries & packages
Open in ThreatlineRecord JSON
CVSS
7.5High
ExploitationNo known exploitationNot in CISA KEV, which does not prove it is unexploitedCISA KEV
Exploit odds (EPSS)1.03%Chance of exploitation activity in the next 30 days, higher than 63% of CVEs. Scored 23 Oct 2026FIRST EPSS
Fixed in10.0.13Also 11.0.0-rc.2, 8.0.5 and 9 moreGitHub
Published13 Oct 2026Updated 23 Oct 2026CVE List

What fixes it

  • 10.0.13System.Security.Cryptography.Xml, nugetGitHubdotnet add package System.Security.Cryptography.Xml --version 10.0.13
  • 11.0.0-rc.2System.Security.Cryptography.Xml, nugetGitHubdotnet add package System.Security.Cryptography.Xml --version 11.0.0-rc.2
  • 8.0.5System.Security.Cryptography.Xml, nugetGitHubdotnet add package System.Security.Cryptography.Xml --version 8.0.5
  • 9.0.21System.Security.Cryptography.Xml, nugetGitHubdotnet add package System.Security.Cryptography.Xml --version 9.0.21
  • 2.0.50727.9188 AND 3.0.30729.9171Microsoft .NET Framework 3.5CVE List
  • 2.0.50727.8987 AND 3.0.30729.8982 AND 4.7.4150.0Microsoft .NET Framework 3.5 AND 4.6.2/4.7/4.7.1/4.7.2CVE List
Show all 17 fixed versions
  • 2.0.50727.9073 AND 3.0.30729.9070 AND 4.7.4150.0Microsoft .NET Framework 3.5 AND 4.7.2CVE List
  • 2.0.50727.9073 AND 3.0.30729.9070 AND 4.8.4811.0Microsoft .NET Framework 3.5 AND 4.8CVE List
  • 2.0.50727.9188 AND 3.0.30729.9171 AND 4.8.9363.0Microsoft .NET Framework 3.5 AND 4.8.1CVE List
  • 4.7.4150.0Microsoft .NET Framework 4.6.2/4.7/4.7.1/4.7.2CVE List
  • 4.8.4811.0Microsoft .NET Framework 4.8CVE List
  • 4.8.9363.0Microsoft .NET Framework 4.8.1CVE List
  • 10.0.13System.Security.Cryptography.XmlCVE List
  • 10.0.13System.Security.Cryptography.Xml, NuGetOSVdotnet add package System.Security.Cryptography.Xml --version 10.0.13
  • 11.0.0-rc.2System.Security.Cryptography.Xml, NuGetOSVdotnet add package System.Security.Cryptography.Xml --version 11.0.0-rc.2
  • 8.0.5System.Security.Cryptography.Xml, NuGetOSVdotnet add package System.Security.Cryptography.Xml --version 8.0.5
  • 9.0.21System.Security.Cryptography.Xml, NuGetOSVdotnet add package System.Security.Cryptography.Xml --version 9.0.21

A fixed version on one release line is not the upgrade target for every line. Check your exact version and any vendor backports.

Vendor and government advisories 1

Vendors that say their products are affected, and agencies that issued alerts. Check each for the fixed release of the product you run.

Reports 1

1 outlet mention it. Reports are not confirmation; each links to its source.

Description

Executive summary

Microsoft is releasing this security advisory to provide information about a vulnerability in System.Security.Cryptography.Xml; System.Private.Xml. This advisory also provides guidance on what developers can do to update their applications to remove this vulnerability.

Signed XML fixes add input-depth and operation-count limits, prohibit DTD processing by default, validate entity references, bound encrypted-data candidate processing, and cap attributes and namespaces used by C14N transforms.

Announcement

Announcement for this issue can be found at https://github.com/dotnet/announcements/issues/488

CVSS Details

  • Version: 3.1
  • Severity: High
  • Score: 7.5
  • Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
  • Weakness: CWE-407 (Inefficient Algorithmic Complexity)

Affected Platforms

  • Platforms: Windows, Linux, macOS
  • Architectures: All

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

The vulnerability affects Microsoft .NET projects that use an affected package version listed below.

Package name | Affected version | Patched version ------------ | ---------------- | --------------- System.Security.Cryptography.Xml | >= 10.0.0, <= 10.0.12 | 10.0.13 System.Security.Cryptography.Xml | >= 11.0.0-preview.1, <= 11.0.0-rc.1 | 11.0.0-rc.2 System.Security.Cryptography.Xml | >= 8.0.0, <= 8.0.4 | 8.0.5 System.Security.Cryptography.Xml | >= 9.0.0, <= 9.0.20 | 9.0.21

Advisory FAQ

<a name="how-affected"></a>How do I know if I am affected?

If using a package listed in [affected packages](#affected-packages), you're exposed to the vulnerability.

<a name="how-fix"></a>How do I fix the issue?

  1. To fix the issue please install the latest version of .NET. If you have installed one or more .NET SDKs through Visual Studio, Visual Studio will prompt you to update Visual Studio, which will also update your .NET SDKs.
  2. If your application references the vulnerable package, update the package reference to the patched version. You can list the versions you have installed by running the dotnet --info command.

Once you have installed the updated runtime or SDK, restart your apps for the update to take effect.

Additionally, if you've deployed self-contained applications targeting any of the impacted versions, these applications are also vulnerable and must be recompiled and redeployed.

Other Information

Reporting Security Issues

If you have found a potential security issue in a supported version of .NET, please report it to the Microsoft Security Response Center (MSRC) via the MSRC Researcher Portal. Further information can be found in the MSRC Report an Issue FAQ.

Security reports made through MSRC may qualify for the Microsoft .NET Bounty. Details of the Microsoft .NET Bounty Program including terms and conditions are at https://aka.ms/corebounty.

Support

You can ask questions about this issue on GitHub in the .NET GitHub organization. The main repos are located at https://github.com/dotnet/runtime. The Announcements repo (https://github.com/dotnet/Announcements) will contain this bulletin as an issue and will include a link to a discussion issue. You can ask questions in the linked discussion issue.

Disclaimer

The information provided in this advisory is provided "as is" without warranty of any kind. Microsoft disclaims all warranties, either express or implied, including the warranties of merchantability and fitness for a particular purpose. In no event shall Microsoft Corporation or its suppliers be liable for any damages whatsoever including direct, indirect, incidental, consequential, loss of business profits or special damages, even if Microsoft Corporation or its suppliers have been advised of the possibility of such damages. Some states do not allow the exclusion or limitation of liability for consequential or incidental damages so the foregoing limitation may not apply.

External Links

CVE-2026-96958

Acknowledgements

  • Mateusz Gierblinski with Curios
  • Leandro Batista
  • Kevin Schmidt
  • Dr.-Ing Ashar Javed (@soaj1664ashar)

Revisions

V1.0 (10/13/2026): Advisory published.

Text from GitHub Advisory Database

Affected versions 56

  • System.Security.Cryptography.Xml, nuget>= 10.0.0, <= 10.0.12GitHub
  • System.Security.Cryptography.Xml, nuget>= 11.0.0-preview.1, <= 11.0.0-rc.1GitHub
  • System.Security.Cryptography.Xml, nuget>= 8.0.0, <= 8.0.4GitHub
  • System.Security.Cryptography.Xml, nuget>= 9.0.0, <= 9.0.20GitHub
  • Microsoft .NET Framework 3.5affected: 3.5.0 before 2.0.50727.9188 AND 3.0.30729.9171CVE List
  • Microsoft .NET Framework 3.5 AND 4.6.2/4.7/4.7.1/4.7.2affected: 3.0.0.0 before 2.0.50727.8987 AND 3.0.30729.8982 AND 4.7.4150.0CVE List
  • Microsoft .NET Framework 3.5 AND 4.7.2affected: 4.7.0 before 2.0.50727.9073 AND 3.0.30729.9070 AND 4.7.4150.0CVE List
  • Microsoft .NET Framework 3.5 AND 4.8affected: 4.8.0 before 2.0.50727.9073 AND 3.0.30729.9070 AND 4.8.4811.0CVE List
  • Microsoft .NET Framework 3.5 AND 4.8.1affected: 4.8.1 before 2.0.50727.9188 AND 3.0.30729.9171 AND 4.8.9363.0CVE List
  • Microsoft .NET Framework 4.6.2/4.7/4.7.1/4.7.2affected: 4.7.0 before 4.7.4150.0CVE List
  • Microsoft .NET Framework 4.8affected: 4.8.0 before 4.8.4811.0CVE List
  • Microsoft .NET Framework 4.8.1affected: 4.8.0.0 before 4.8.9363.0CVE List
  • System.Security.Cryptography.Xmlaffected: 10.0.0 before 10.0.13CVE List
  • System.Security.Cryptography.Xml, NuGetfrom 10.0.0, fixed in 10.0.13OSV
  • System.Security.Cryptography.Xml, NuGet10.0.0OSV
  • System.Security.Cryptography.Xml, NuGet10.0.1OSV
  • System.Security.Cryptography.Xml, NuGet10.0.10OSV
  • System.Security.Cryptography.Xml, NuGet10.0.11OSV
  • System.Security.Cryptography.Xml, NuGet10.0.12OSV
  • System.Security.Cryptography.Xml, NuGet10.0.2OSV
  • System.Security.Cryptography.Xml, NuGet10.0.3OSV
  • System.Security.Cryptography.Xml, NuGet10.0.4OSV
  • System.Security.Cryptography.Xml, NuGet10.0.5OSV
  • System.Security.Cryptography.Xml, NuGet10.0.6OSV
  • System.Security.Cryptography.Xml, NuGet10.0.7OSV
  • System.Security.Cryptography.Xml, NuGet10.0.8OSV
  • System.Security.Cryptography.Xml, NuGet10.0.9OSV
  • System.Security.Cryptography.Xml, NuGetfrom 11.0.0-preview.1, fixed in 11.0.0-rc.2OSV
  • System.Security.Cryptography.Xml, NuGetfrom 8.0.0, fixed in 8.0.5OSV
  • System.Security.Cryptography.Xml, NuGet8.0.0OSV
  • System.Security.Cryptography.Xml, NuGet8.0.1OSV
  • System.Security.Cryptography.Xml, NuGet8.0.2OSV
  • System.Security.Cryptography.Xml, NuGet8.0.3OSV
  • System.Security.Cryptography.Xml, NuGet8.0.4OSV
  • System.Security.Cryptography.Xml, NuGetfrom 9.0.0, fixed in 9.0.21OSV
  • System.Security.Cryptography.Xml, NuGet9.0.0OSV
  • System.Security.Cryptography.Xml, NuGet9.0.1OSV
  • System.Security.Cryptography.Xml, NuGet9.0.10OSV
  • System.Security.Cryptography.Xml, NuGet9.0.11OSV
  • System.Security.Cryptography.Xml, NuGet9.0.12OSV
  • System.Security.Cryptography.Xml, NuGet9.0.13OSV
  • System.Security.Cryptography.Xml, NuGet9.0.14OSV
  • System.Security.Cryptography.Xml, NuGet9.0.15OSV
  • System.Security.Cryptography.Xml, NuGet9.0.16OSV
  • System.Security.Cryptography.Xml, NuGet9.0.17OSV
  • System.Security.Cryptography.Xml, NuGet9.0.18OSV
  • System.Security.Cryptography.Xml, NuGet9.0.19OSV
  • System.Security.Cryptography.Xml, NuGet9.0.2OSV
  • System.Security.Cryptography.Xml, NuGet9.0.20OSV
  • System.Security.Cryptography.Xml, NuGet9.0.3OSV
  • System.Security.Cryptography.Xml, NuGet9.0.4OSV
  • System.Security.Cryptography.Xml, NuGet9.0.5OSV
  • System.Security.Cryptography.Xml, NuGet9.0.6OSV
  • System.Security.Cryptography.Xml, NuGet9.0.7OSV
  • System.Security.Cryptography.Xml, NuGet9.0.8OSV
  • System.Security.Cryptography.Xml, NuGet9.0.9OSV

References 6