GHSA-rg75-q538-x34v BIT-dotnet-2026-32175 BIT-dotnet-sdk-2026-32175 CVE-2026-32175
Microsoft Security Advisory CVE-2026-32175 – .NET Core Tampering Vulnerability
- Severity
- 7.5 / 10
- Medium · CVSS 3.1
- Exploit chance (EPSS)
- 0.71%
- Chance of exploitation in the next 30 days. Higher than 53.59% of scored vulnerabilities.
- Known exploited
- No
- Not in CISA's catalog
- Weakness
- CWE-22 Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
- CWE-36 Absolute Path Traversal
- Fix
- Available
- 4 packages have a fixed version
Description
Executive Summary:
Microsoft is releasing this security advisory to provide information about a vulnerability in .NET 8.0, .NET 9.0, and .NET 10.0. This advisory also provides guidance on what developers can do to update their applications to remove this vulnerability.
A tampering vulnerability exists when .NET Core improperly handles specially crafted files. An attacker who successfully exploited this vulnerability could write arbitrary files and directories to certain locations on a vulnerable system. However, an attacker would have limited control over the destination of the files and directories.
To exploit the vulnerability, an attacker must send a specially crafted file to a vulnerable system.
The security update fixes the vulnerability by ensuring .NET Core properly handles files.
Announcement
Announcement for this issue can be found at https://github.com/dotnet/announcements/issues/396
CVSS Details
- Version: 3.1
- Severity:
- Score: 4.3
- Vector: /AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
- Weakness: CWE-36: Absolute Path Traversal
Affected Platforms
- Platforms: Windows
- Architectures: All
<a name="affected-packages"></a>Affected Packages
The vulnerability affects any Microsoft .NET project if it uses any of affected package versions listed below
<a name=".NET 10"></a>.NET 10
| Package name | Affected version | Patched version |
|---|---|---|
| Microsoft.NetCore.App.Runtime.win-arm | >= 10.0.0, <= 10.0.7 | 10.0.8 |
| Microsoft.NetCore.App.Runtime.win-arm64 | >= 10.0.0, <= 10.0.7 | 10.0.8 |
| Microsoft.NetCore.App.Runtime.win-x64 | >= 10.0.0, <= 10.0.7 | 10.0.8 |
| Microsoft.NetCore.App.Runtime.win-x86 | >= 10.0.0, <= 10.0.7 | 10.0.8 |
<a name=".NET 9"></a>.NET 9
| Package name | Affected version | Patched version |
|---|---|---|
| Microsoft.NetCore.App.Runtime.win-arm | >= 9.0.0, <= 9.0.15 | 9.0.16 |
| Microsoft.NetCore.App.Runtime.win-arm64 | >= 9.0.0, <= 9.0.15 | 9.0.16 |
| Microsoft.NetCore.App.Runtime.win-x64 | >= 9.0.0, <= 9.0.15 | 9.0.16 |
| Microsoft.NetCore.App.Runtime.win-x86 | >= 9.0.0, <= 9.0.15 | 9.0.16 |
<a name=".NET 8"></a>.NET 8
| Package name | Affected version | Patched version |
|---|---|---|
| Microsoft.NetCore.App.Runtime.win-arm | >= 8.0.0, <= 8.0.26 | 8.0.27 |
| Microsoft.NetCore.App.Runtime.win-arm64 | >= 8.0.0, <= 8.0.26 | 8.0.27 |
| Microsoft.NetCore.App.Runtime.win-x64 | >= 8.0.0, <= 8.0.26 | 8.0.27 |
| Microsoft.NetCore.App.Runtime.win-x86 | >= 8.0.0, <= 8.0.26 | 8.0.27 |
Advisory FAQ
<a name="how-affected"></a>How do I know if I am affected?
If using a package listed in affected packages, a developer's application is exposed to the vulnerability.
<a name="how-fix"></a>How do I fix the issue?
- To fix the issue please install the latest version of .NET 8.0, NET 9.0, or .NET 10.0, as appropriate. If developers have installed one or more .NET SDKs through Visual Studio, Visual Studio will prompt them to update Visual Studio, which will also update their .NET SDKs.
- If a developer's application references the vulnerable package, update the package reference to the patched version. Developers can list the versions they have installed by running the
dotnet --infocommand.
Once developers have installed the updated runtime or SDK, they can restart their apps for the update to take effect.
Additionally, if they'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 someone has 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
Questions about this issue can be directed to 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. Questions should be submitted to 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
Revisions
V1.0 (May 12, 2026): Advisory published.
Affected versions
NuGet
| Package | Vulnerable | Fixed in |
|---|---|---|
| Microsoft.NetCore.App.Runtime.win-arm | >= 8.0.0, < 8.0.27 |
8.0.27 |
| Microsoft.NetCore.App.Runtime.win-arm | >= 9.0.0, < 9.0.16 |
9.0.16 |
| Microsoft.NetCore.App.Runtime.win-arm | >= 10.0.0, < 10.0.8 |
10.0.8 |
| Microsoft.NetCore.App.Runtime.win-arm64 | >= 8.0.0, < 8.0.27 |
8.0.27 |
| Microsoft.NetCore.App.Runtime.win-arm64 | >= 9.0.0, < 9.0.16 |
9.0.16 |
| Microsoft.NetCore.App.Runtime.win-arm64 | >= 10.0.0, < 10.0.8 |
10.0.8 |
| Microsoft.NetCore.App.Runtime.win-x64 | >= 8.0.0, < 8.0.27 |
8.0.27 |
| Microsoft.NetCore.App.Runtime.win-x64 | >= 9.0.0, < 9.0.16 |
9.0.16 |
| Microsoft.NetCore.App.Runtime.win-x64 | >= 10.0.0, < 10.0.8 |
10.0.8 |
| Microsoft.NetCore.App.Runtime.win-x86 | >= 8.0.0, < 8.0.27 |
8.0.27 |
| Microsoft.NetCore.App.Runtime.win-x86 | >= 9.0.0, < 9.0.16 |
9.0.16 |
| Microsoft.NetCore.App.Runtime.win-x86 | >= 10.0.0, < 10.0.8 |
10.0.8 |
How to fix
Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.
Microsoft.NetCore.App.Runtime.win-arm NuGet → 8.0.27
- dotnet
dotnet add package Microsoft.NetCore.App.Runtime.win-arm --version 8.0.27
Microsoft.NetCore.App.Runtime.win-arm64 NuGet → 8.0.27
- dotnet
dotnet add package Microsoft.NetCore.App.Runtime.win-arm64 --version 8.0.27
Microsoft.NetCore.App.Runtime.win-x64 NuGet → 8.0.27
- dotnet
dotnet add package Microsoft.NetCore.App.Runtime.win-x64 --version 8.0.27
Microsoft.NetCore.App.Runtime.win-x86 NuGet → 8.0.27
- dotnet
dotnet add package Microsoft.NetCore.App.Runtime.win-x86 --version 8.0.27
Severity breakdown
CVSS 3.1 7.5
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- High
- Availability
- None
Weakness
CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.
How to prevent it
- Implementation: Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does. When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue." Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright. When validating filenames, use stringent allowlists that limit the character set to be used. If feasible, only allow a single "." character in the filename to avoid weaknesses such as CWE-23, and exclude directory separators such as "/" to avoid CWE-36. Use a list of allowable file extensions, which will help to avoid CWE-434. Do not rely exclusively on a filtering mechanism that removes potentially dangerous characters. This is equivalent to a denylist, which may be incomplete (CWE-184). For example, filtering "/" is insufficient protection if the filesystem also supports the use of "\" as a directory separator. Another possible error could occur when the filtering is applied in a way that still produces dangerous data (CWE-182). For example, if "../" sequences are removed from the ".../...//" string in a sequential fashion, two instances of "../" would b
- Architecture and Design: For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.
- Implementation: Inputs should be decoded and canonicalized to the application's current internal representation before being validated (CWE-180). Make sure that the application does not decode the same input twice (CWE-174). Such errors could be used to bypass allowlist validation schemes by introducing dangerous inputs after they have been checked. Use a built-in path canonicalization function (such as realpath() in C) that produces the canonical version of the pathname, which effectively removes ".." sequences and symbolic links (CWE-23, CWE-59). This includes: realpath() in C getCanonicalPath() in Java GetFullPath() in ASP.NET realpath() or abs_path() in Perl realpath() in PHP
- Architecture and Design: Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid [REF-1482].
- Operation: Use an application firewall that can detect attacks against this weakness. It can be beneficial in cases in which the code cannot be fixed (because it is controlled by a third party), as an emergency prevention measure while more comprehensive software assurance measures are applied, or to provide defense in depth [REF-1481].
- Architecture and Design, Operation: Run your code using the lowest privileges that are required to accomplish the necessary tasks [REF-76]. If possible, create isolated accounts with limited privileges that are only used for a single task. That way, a successful attack will not immediately give the attacker access to the rest of the software or its environment. For example, database applications rarely need to run as the database administrator, especially in day-to-day operations.
- Architecture and Design: When the set of acceptable objects, such as filenames or URLs, is limited or known, create a mapping from a set of fixed input values (such as numeric IDs) to the actual filenames or URLs, and reject all other inputs. For example, ID 1 could map to "inbox.txt" and ID 2 could map to "profile.txt". Features such as the ESAPI AccessReferenceMap [REF-185] provide this capability.
- Architecture and Design, Operation: Run the code in a "jail" or similar sandbox environment that enforces strict boundaries between the process and the operating system. This may effectively restrict which files can be accessed in a particular directory or which commands can be executed by the software. OS-level examples include the Unix chroot jail, AppArmor, and SELinux. In general, managed code may provide some protection. For example, java.io.FilePermission in the Java SecurityManager allows the software to specify restrictions on file operations. This may not be a feasible solution, and it only limits the impact to the operating system; the rest of the application may still be subject to compromise. Be careful to avoid CWE-243 and other weaknesses related to jails.
- Architecture and Design, Operation: Store library, include, and utility files outside of the web document root, if possible. Otherwise, store them in a separate directory and use the web server's access control capabilities to prevent attackers from directly requesting them. One common practice is to define a fixed constant in each calling program, then check for the existence of the constant in the library/include file; if the constant does not exist, then the file was directly requested, and it can exit immediately. This significantly reduces the chance of an attacker being able to bypass any protection mechanisms that are in the base program but not in the include files. It will also reduce the attack surface.
- Implementation: Ensure that error messages only contain minimal details that are useful to the intended audience and no one else. The messages need to strike the balance between being too cryptic (which can confuse users) or being too detailed (which may reveal more than intended). The messages should not reveal the methods that were used to determine the error. Attackers can use detailed information to refine or optimize their original attack, thereby increasing their chances of success. If errors must be captured in some detail, record them in log messages, but consider what could occur if the log messages can be viewed by attackers. Highly sensitive information such as passwords should never be saved to log files. Avoid inconsistent messaging that might accidentally tip off an attacker about internal state, such as whether a user account exists or not. In the context of path traversal, error messages which disclose path information can help attackers craft the appropriate attack strings to move through the file system hierarchy.
- Operation, Implementation: When using PHP, configure the application so that it does not use register_globals. During implementation, develop the application so that it does not rely on this feature, but be wary of implementing a register_globals emulation that is subject to weaknesses such as CWE-95, CWE-621, and similar issues.
CWE-36: Absolute Path Traversal
The product uses external input to construct a pathname that should be within a restricted directory, but it does not properly neutralize absolute path sequences such as "/abs/path" that can resolve to a location that is outside of that directory.
How to prevent it
- Implementation: Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does. When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue." Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright. When validating filenames, use stringent allowlists that limit the character set to be used. If feasible, only allow a single "." character in the filename to avoid weaknesses such as CWE-23, and exclude directory separators such as "/" to avoid CWE-36. Use a list of allowable file extensions, which will help to avoid CWE-434. Do not rely exclusively on a filtering mechanism that removes potentially dangerous characters. This is equivalent to a denylist, which may be incomplete (CWE-184). For example, filtering "/" is insufficient protection if the filesystem also supports the use of "\" as a directory separator. Another possible error could occur when the filtering is applied in a way that still produces dangerous data (CWE-182). For example, if "../" sequences are removed from the ".../...//" string in a sequential fashion, two instances of "../" would b
- Implementation: Inputs should be decoded and canonicalized to the application's current internal representation before being validated (CWE-180). Make sure that the application does not decode the same input twice (CWE-174). Such errors could be used to bypass allowlist validation schemes by introducing dangerous inputs after they have been checked.
- Operation: Use an application firewall that can detect attacks against this weakness. It can be beneficial in cases in which the code cannot be fixed (because it is controlled by a third party), as an emergency prevention measure while more comprehensive software assurance measures are applied, or to provide defense in depth [REF-1481].
References
Advisories
Packages
Other links
Timeline
- Published
- Last updated by the source
- Latest EPSS score
Related advisories
| Advisory | Severity | Why it's related |
|---|---|---|
| CVE-2020-1147 .NET Framework, SharePoint Server, and Visual Studio Remote Code Execution Vulnerability | High Known exploited | Also affects Microsoft.NETCore.App.Runtime.win-arm |
| GHSA-87vj-4hqv-22p9 Microsoft Security Advisory CVE-2026-96233 - .NET and Visual Studio Denial of Service Vulnerability | High | Also affects Microsoft.NETCore.App.Runtime.win-arm |
| GHSA-4mpw-cpwj-hxxj Microsoft Security Advisory CVE-2026-70197 - .NET and Visual Studio Remote Code Execution Vulnerability | High | Also affects Microsoft.NETCore.App.Runtime.win-arm64 |
| GHSA-3rxq-g8rj-r2cf Microsoft Security Advisory CVE-2026-69651 - .NET and Visual Studio Denial of Service Vulnerability | High | Also affects Microsoft.NETCore.App.Runtime.win-arm64 |
| GHSA-wxxw-5cvc-53j7 Microsoft Security Advisory CVE-2026-66822 - .NET and Visual Studio Information Disclosure Vulnerability | Medium | Also affects Microsoft.NETCore.App.Runtime.win-arm64 |
| GHSA-mc4q-93x5-f6hj Microsoft Security Advisory CVE-2026-58280 - .NET and Visual Studio Denial of Service Vulnerability | High | Also affects Microsoft.NETCore.App.Runtime.win-arm |
| GHSA-m93f-wj8c-rp8p Microsoft Security Advisory CVE-2026-62901 – .NET Denial of Service Vulnerability | High | Also affects Microsoft.NETCore.App.Runtime.win-arm64 |
| GHSA-c494-m2fq-59mx Microsoft Security Advisory CVE-2026-62898 – .NET Information Disclosure Vulnerability | High | Also affects Microsoft.NETCore.App.Runtime.win-arm64 |
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