.NET Tampering Vulnerability

CISA KEV lists vulnerabilities known to be exploited. FIRST EPSS estimates the likelihood of exploitation in the next 30 days. An unavailable score does not mean zero risk.

Improper link resolution before file access ('link following') in .NET allows an unauthorized attacker to perform tampering locally.

Source published

9 Jun 2026 17:04:44 UTC

Source modified

10 Nov 2026 23:23:39 UTC

Saved here

11 Nov 2026 02:25:43 UTC

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CVE Program Terms of Use

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Source: cve-program · CVE Program Terms of Use. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.

CVSS 3.1 · 6.2 CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N/E:U/RL:O/RC:C

Improper link resolution before file access ('link following') in .NET allows an unauthorized attacker to perform tampering locally.

Source published

Jun 9, 2026, 5:04:44 PM (timezone not stated)

Source modified

Nov 10, 2026, 11:23:39 PM (timezone not stated)

Saved here

14 Nov 2026 00:08:49 UTC

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ENISA EUVD · source terms and attribution apply

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Source: euvd · ENISA EUVD · source terms and attribution apply. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.

EUVD CVSS 3.1 · 6.2 CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N/E:U/RL:O/RC:C

Improper link resolution before file access ('link following') in .NET allows an unauthorized attacker to perform tampering locally.

Source published

9 Jun 2026 17:17:25 UTC

Source modified

11 Nov 2026 00:18:59 UTC

Saved here

12 Nov 2026 17:18:54 UTC

Source terms

NIST NVD usage terms; underlying source attribution retained

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Source: nvd · NIST NVD usage terms; underlying source attribution retained. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.

CVSS 3.1 · [email protected] · Secondary · 6.2 CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

CVSS 3.1 · [email protected] · Primary · 5.5 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N

## Executive Summary Microsoft is releasing this security advisory to provide information about a vulnerability in System.Formats.Tar. This advisory also provides guidance on what developers can do to update their applications to remove this vulnerability. A tampering vulnerability exists in the `TarFile.ExtractToDirectory` method where a symlink path traversal enables an attacker to perform arbitrary file writes outside the intended extraction directory. ## Announcement Announcement for this issue can be found at https://github.com/dotnet/announcements/issues/404 ## Affected Platforms - **Platforms:** All - **Architectures:** All ## Affected Packages The vulnerability affects any Microsoft .NET project if it uses any of affected package versions listed below ### .NET 10 Package name | Affected version | Patched version ------------ | ---------------- | ------------------------- [Microsoft.NETCore.App.Runtime](https://www.nuget.org/packages/Microsoft.NETCore.App.Runtime) | >= 10.0.0, <= 10.0.8 | 10.0.9 ### .NET 9 Package name | Affected version | Patched version ------------ | ---------------- | ------------------------- [Microsoft.NETCore.App.Runtime](https://www.nuget.org/packages/Microsoft.NETCore.App.Runtime) | >= 9.0.0, <= 9.0.16 | 9.0.17 ### .NET 8 Package name | Affected version | Patched version ------------ | ---------------- | ------------------------- [Microsoft.NETCore.App.Runtime](https://www.nuget.org/packages/Microsoft.NETCore.App.Runtime) | >= 8.0.0, <= 8.0.27 | 8.0.28 ## Advisory FAQ ### How do I know if I am affected? If using a package listed in affected packages, you're exposed to the vulnerability. ### How do I fix the issue? 1. To fix the issue please install the latest version of .NET 8.0, .NET 9.0, or .NET 10.0, as appropriate. 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. 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](https://docs.microsoft.com/dotnet/core/deploying/#self-contained-deployments-scd) 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](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. ### Acknowledgements Anonymous, Ashmit Sharma, Ky0toFu ,phrolo7a ### Revisions V1.0 (June 9, 2026): Advisory published.

Source published

16 Jun 2026 14:33:40 UTC

Source modified

10 Sep 2026 03:50:50 UTC

Saved here

23 Oct 2026 16:01:25 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

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Source: osv · GitHub Advisory Database · CC-BY-4.0. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.

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

Publisher rating · MODERATE