.NET Denial of Service Vulnerability

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

Uncontrolled resource consumption in .NET allows an unauthorized attacker to deny service over a network.

Source published

14 Apr 2026 16:58:37 UTC

Source modified

15 Oct 2026 15:53:38 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: cve-program · CVE Program Terms of Use. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 3.1 · 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C

Uncontrolled resource consumption in .NET allows an unauthorized attacker to deny service over a network.

Source published

Apr 14, 2026, 4:58:37 PM (timezone not stated)

Source modified

Oct 15, 2026, 3:53:38 PM (timezone not stated)

Observed here

1 Nov 2026 04:05:26 UTC

Source terms

ENISA EUVD · source terms and attribution apply

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: euvd · ENISA EUVD · source terms and attribution apply. Source text is retained; field grouping and change labels are provided by ChangeIntel.

EUVD CVSS 3.1 · 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C

Uncontrolled resource consumption in .NET allows an unauthorized attacker to deny service over a network.

Source published

14 Apr 2026 18:16:51 UTC

Source modified

26 Oct 2026 22:10:00 UTC

Observed here

27 Oct 2026 07:23:21 UTC

Source terms

NIST NVD usage terms; underlying source attribution retained

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: nvd · NIST NVD usage terms; underlying source attribution retained. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 3.1 · [email protected] · Secondary · 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS 3.1 · 0b0ca135-0b70-47e7-9f44-1890c2a1c46c · Secondary · 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

## Executive Summary: Microsoft is releasing this security advisory to provide information about a vulnerability in System.Security.Cryptography.Xml. This advisory also provides guidance on what developers can do to update their applications to remove this vulnerability. A vulnerability exists in EncryptedXml class where uncontrolled resource consumption can give an attacker to the ability to perform a Denial of Service attack. ## Announcement Announcement for this issue can be found at https://github.com/dotnet/announcements/issues/389 ## CVSS Details - **Version:** 3.1 - **Severity:** High - **Score:** 7.5 - **Vector:** 7.5: AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H E:U/RL:O/RC:C - **Weakness:** CWE-400 CWE-611: Uncontrolled Resource Consumption Improper Restriction of XML External Entity Reference ## Affected Platforms - **Platforms:** All - **Architectures:** All ## <a name="affected-packages"></a>Affected Packages The vulnerability affects any Microsoft .NET project if it uses any of affected packages versions listed below ### <a name=".NET 10"></a>.NET 10 Package name | Affected version | Patched version ------------ | ---------------- | ------------------------- [System.Security.Cryptography.xml](https://www.nuget.org/packages/System.Security.Cryptography.Xml) | >=10.0.0, <=10.0.5; | 10.0.6 ### <a name=".NET 9"></a>.NET 9 Package name | Affected version | Patched version ------------ | ---------------- | ------------------------- [System.Security.Cryptography.xml](https://www.nuget.org/packages/System.Security.Cryptography.Xml) | >=9.0.0, <=9.0.14; | 9.0.15 ### <a name=".NET 8"></a>.NET 8 Package name | Affected version | Patched version ------------ | ---------------- | ------------------------- [System.Security.Cryptography.xml](https://www.nuget.org/packages/System.Security.Cryptography.Xml) | >=8.0.0, <=8.0.2; | 8.0.3 ## Advisory FAQ ### <a name="how-affected"></a>How do I know if I am affected? If using an affected package listed in [affected packages](#affected-packages), you're exposed to the vulnerability. ### <a name="how-fix"></a>How do I fix the issue? To update the Using the System.Security.Cryptography.Xml NuGet package, use one of the following methods: NuGet Package Manager UI in Visual Studio: - Open your project in Visual Studio. - Right-click on your project in Solution Explorer and select "Manage NuGet Packages..." or navigate to "Project > Manage NuGet Packages". - In the NuGet Package Manager window, select the "Updates" tab. This tab lists packages with available updates from your configured package sources. - Select the package(s) you wish to update. You can choose a specific version from the dropdown or update to the latest available version. - Click the "Update" button. Using the NuGet Package Manager Console in Visual Studio: - Open your project in Visual Studio. - Navigate to "Tools > NuGet Package Manager > Package Manager Console". - To update a specific package to its latest version, use the following Update-Package command: ```Update-Package -Id System.Security.Cryptography.xml``` Using the .NET CLI (Command Line Interface): - Open a terminal or command prompt in your project's directory. - To update a specific package to its latest version, use the following add package command: ```dotnet add package System.Security.Cryptography.Xml``` Once you have updated the nuget package reference you must recompile and deploy your application. Additionally we recommend you update your runtime and/or SDKs, but it is not necessary to patch the vulnerability. ## 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](https://msrc.microsoft.com/report/vulnerability/new). Further information can be found in the MSRC [Report an Issue FAQ](https://www.microsoft.com/msrc/faqs-report-an-issue). 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-2026-26171](https://www.cve.org/CVERecord?id=CVE-2026-26171) ### Acknowledgements Ludvig Pedersen ### Revisions V1.0 (April 14, 2026): Advisory published.

Source published

14 Apr 2026 23:31:08 UTC

Source modified

10 Sep 2026 03:51:03 UTC

Observed here

23 Oct 2026 16:01:25 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V3 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Publisher rating · HIGH