GHSA-8x9c-mqxv-q2pp BIT-dotnet-2026-35433 BIT-dotnet-sdk-2026-35433 CVE-2026-35433
Microsoft Security Advisory CVE-2026-35433 – .NET Elevation of Privilege Vulnerability
- Severity
- 7.3 / 10
- High · CVSS 3.1
- Exploit chance (EPSS)
- 0.77%
- Chance of exploitation in the next 30 days. Higher than 55.52% of scored vulnerabilities.
- Known exploited
- No
- Not in CISA's catalog
- Fix
- Available
- 3 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.
Improper input validation in .NET allows an unauthorized attacker to elevate privileges locally.
Announcement
Announcement for this issue can be found at https://github.com/dotnet/announcements/issues/398
CVSS Details
- Version: 3.1
- Severity: High
- Score: 7.3
- Vector: AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:L/E:U/RL:O/RC:C
- Weakness: CWE-122: Heap-based Buffer Overflow, CWE-20: Improper Input Validation
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.WindowsDesktop.App.Runtime.win-arm64 | >= 10.0.0, <= 10.0.7 | 10.0.8 |
| Microsoft.WindowsDesktop.App.Runtime.win-x64 | >= 10.0.0, <= 10.0.7 | 10.0.8 |
| Microsoft.WindowsDesktop.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.WindowsDesktop.App.Runtime.win-arm64 | >= 9.0.0, <= 9.0.15 | 9.0.16 |
| MMicrosoft.WindowsDesktop.App.Runtime.win-x64 | >= 9.0.0, <= 9.0.15 | 9.0.16 |
| Microsoft.WindowsDesktop.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.WindowsDesktop.App.Runtime.win-arm64 | >= 8.0.0, <= 8.0.26 | 8.0.27 |
| MMicrosoft.WindowsDesktop.App.Runtime.win-x64 | >= 8.0.0, <= 8.0.26 | 8.0.27 |
| Microsoft.WindowsDesktop.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, an 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 the applications's .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 the app for the update to take effect.
Additionally, if developers have 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
A potential security issue has been found 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 submitted 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 thorugh 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
Acknowledgements
Ky0toFu
Revisions
V1.0 (May 12, 2026): Advisory published.
Affected versions
NuGet
| Package | Vulnerable | Fixed in |
|---|---|---|
| Microsoft.WindowsDesktop.App.Runtime.win-arm64 | >= 8.0.0, < 8.0.27 |
8.0.27 |
| Microsoft.WindowsDesktop.App.Runtime.win-arm64 | >= 9.0.0, < 9.0.16 |
9.0.16 |
| Microsoft.WindowsDesktop.App.Runtime.win-arm64 | >= 10.0.0, < 10.0.8 |
10.0.8 |
| Microsoft.WindowsDesktop.App.Runtime.win-x64 | >= 8.0.0, < 8.0.27 |
8.0.27 |
| Microsoft.WindowsDesktop.App.Runtime.win-x64 | >= 9.0.0, < 9.0.16 |
9.0.16 |
| Microsoft.WindowsDesktop.App.Runtime.win-x64 | >= 10.0.0, < 10.0.8 |
10.0.8 |
| Microsoft.WindowsDesktop.App.Runtime.win-x86 | >= 8.0.0, < 8.0.27 |
8.0.27 |
| Microsoft.WindowsDesktop.App.Runtime.win-x86 | >= 9.0.0, < 9.0.16 |
9.0.16 |
| Microsoft.WindowsDesktop.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.WindowsDesktop.App.Runtime.win-arm64 NuGet → 8.0.27
- dotnet
dotnet add package Microsoft.WindowsDesktop.App.Runtime.win-arm64 --version 8.0.27
Microsoft.WindowsDesktop.App.Runtime.win-x64 NuGet → 8.0.27
- dotnet
dotnet add package Microsoft.WindowsDesktop.App.Runtime.win-x64 --version 8.0.27
Microsoft.WindowsDesktop.App.Runtime.win-x86 NuGet → 8.0.27
- dotnet
dotnet add package Microsoft.WindowsDesktop.App.Runtime.win-x86 --version 8.0.27
Severity breakdown
CVSS 3.1 7.3
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:L
- Attack vector
- Local
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- Required
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- Low
Weakness
CWE-122: Heap-based Buffer Overflow
A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc().
How to prevent it
- Pre-design: Use a language or compiler that performs automatic bounds checking.
- Architecture and Design: Use an abstraction library to abstract away risky APIs. Not a complete solution.
- Operation, Build and Compilation: Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index checking. D3-SFCV (Stack Frame Canary Validation) from D3FEND [REF-1334] discusses canary-based detection in detail.
- Operation, Build and Compilation: Run or compile the software using features or extensions that randomly arrange the positions of a program's executable and libraries in memory. Because this makes the addresses unpredictable, it can prevent an attacker from reliably jumping to exploitable code. Examples include Address Space Layout Randomization (ASLR) [REF-58] [REF-60] and Position-Independent Executables (PIE) [REF-64]. Imported modules may be similarly realigned if their default memory addresses conflict with other modules, in a process known as "rebasing" (for Windows) and "prelinking" (for Linux) [REF-1332] using randomly generated addresses. ASLR for libraries cannot be used in conjunction with prelink since it would require relocating the libraries at run-time, defeating the whole purpose of prelinking. For more information on these techniques see D3-SAOR (Segment Address Offset Randomization) from D3FEND [REF-1335].
- Implementation: Implement and perform bounds checking on input.
- Implementation: Do not use dangerous functions such as gets. Look for their safe equivalent, which checks for the boundary.
- Operation: Use OS-level preventative functionality. This is not a complete solution, but it provides some defense in depth.
CWE-20: Improper Input Validation
The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.
How to prevent it
- Architecture and Design: Consider using language-theoretic security (LangSec) techniques that characterize inputs using a formal language and build "recognizers" for that language. This effectively requires parsing to be a distinct layer that effectively enforces a boundary between raw input and internal data representations, instead of allowing parser code to be scattered throughout the program, where it could be subject to errors or inconsistencies that create weaknesses. [REF-1109] [REF-1110] [REF-1111]
- Architecture and Design: Use an input validation framework such as Struts or the OWASP ESAPI Validation API. Note that using a framework does not automatically address all input validation problems; be mindful of weaknesses that could arise from misusing the framework itself (CWE-1173).
- Architecture and Design, Implementation: Understand all the potential areas where untrusted inputs can enter the product, including but not limited to: parameters or arguments, cookies, anything read from the network, environment variables, reverse DNS lookups, query results, request headers, URL components, e-mail, files, filenames, databases, and any external systems that provide data to the application. Remember that such inputs may be obtained indirectly through API calls.
- 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.
- 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. Even though client-side checks provide minimal benefits with respect to server-side security, they are still useful. First, they can support intrusion detection. If the server receives input that should have been rejected by the client, then it may be an indication of an attack. Second, client-side error-checking can provide helpful feedback to the user about the expectations for valid input. Third, there may be a reduction in server-side processing time for accidental input errors, although this is typically a small savings.
- Implementation: When your application combines data from multiple sources, perform the validation after the sources have been combined. The individual data elements may pass the validation step but violate the intended restrictions after they have been combined.
- Implementation: Be especially careful to validate all input when invoking code that crosses language boundaries, such as from an interpreted language to native code. This could create an unexpected interaction between the language boundaries. Ensure that you are not violating any of the expectations of the language with which you are interfacing. For example, even though Java may not be susceptible to buffer overflows, providing a large argument in a call to native code might trigger an overflow.
- Implementation: Directly convert your input type into the expected data type, such as using a conversion function that translates a string into a number. After converting to the expected data type, ensure that the input's values fall within the expected range of allowable values and that multi-field consistencies are maintained.
- Implementation: Inputs should be decoded and canonicalized to the application's current internal representation before being validated (CWE-180, CWE-181). Make sure that your application does not inadvertently decode the same input twice (CWE-174). Such errors could be used to bypass allowlist schemes by introducing dangerous inputs after they have been checked. Use libraries such as the OWASP ESAPI Canonicalization control. Consider performing repeated canonicalization until your input does not change any more. This will avoid double-decoding and similar scenarios, but it might inadvertently modify inputs that are allowed to contain properly-encoded dangerous content.
- Implementation: When exchanging data between components, ensure that both components are using the same character encoding. Ensure that the proper encoding is applied at each interface. Explicitly set the encoding you are using whenever the protocol allows you to do so.
References
Advisories
Packages
Other links
- github.com/dotnet/wpf/security/advisories/GHSA-8x9c-mqxv-q2pp
- github.com/dotnet/announcements/issues/398
- access.redhat.com/security/cve/CVE-2026-35433
- bugzilla.redhat.com/show_bug.cgi
- msrc.microsoft.com/update-guide/vulnerability/CVE-2026-35433
- security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-35433.json
Timeline
- Published
- Last updated by the source
- Latest EPSS score
Related advisories
| Advisory | Severity | Why it's related |
|---|---|---|
| GHSA-g44w-h65v-4cw9 Microsoft Security Advisory CVE-2026-96235 - .NET and Visual Studio Remote Code Execution Vulnerability | High | Also affects Microsoft.WindowsDesktop.App.Runtime.win-arm64 |
| GHSA-fq6x-pvr9-888r Microsoft Security Advisory CVE-2026-96234 - .NET and Visual Studio Information Disclosure Vulnerability | Medium | Also affects Microsoft.WindowsDesktop.App.Runtime.win-arm64 |
| GHSA-f8qh-mqg4-9939 Microsoft Security Advisory CVE-2026-96232 - .NET and Visual Studio Information Disclosure Vulnerability | High | Also affects Microsoft.WindowsDesktop.App.Runtime.win-arm64 |
| GHSA-5qr9-xxm9-6cmq Microsoft Security Advisory CVE-2026-96229 - .NET and Visual Studio Information Disclosure Vulnerability | Medium | Also affects Microsoft.WindowsDesktop.App.Runtime.win-arm64 |
| GHSA-xq57-crx4-g373 Microsoft Security Advisory CVE-2026-96224 - .NET and Visual Studio Remote Code Execution Vulnerability | High | Also affects Microsoft.WindowsDesktop.App.Runtime.win-arm64 |
| GHSA-c27m-942f-rcfh Microsoft Security Advisory CVE-2026-87697 - .NET and Visual Studio Remote Code Execution Vulnerability | High | Also affects Microsoft.WindowsDesktop.App.Runtime.win-arm64 |
| GHSA-f63g-mx39-3r38 Microsoft Security Advisory CVE-2026-85363 - .NET and Visual Studio Remote Code Execution Vulnerability | High | Also affects Microsoft.WindowsDesktop.App.Runtime.win-arm64 |
| GHSA-4w5f-7jp2-w48g Microsoft Security Advisory CVE-2026-83520 - .NET and Visual Studio Remote Code Execution Vulnerability | High | Also affects Microsoft.WindowsDesktop.App.Runtime.win-arm64 |
MergeHarbor checks every repository's dependencies against this database, ranks what matters by exploitability and reachability, routes it to the owning team and opens the fix pull request.
Check your repos with MergeHarbor