GHSA-c399-9853-6jmj BIT-dotnet-2026-96959 BIT-dotnet-sdk-2026-96959 CVE-2026-96959
Microsoft Security Advisory CVE-2026-96959 - .NET and Visual Studio Denial of Service Vulnerability
- Severity
- 7.5 / 10
- High · CVSS 3.1
- Exploit chance (EPSS)
- 0.97%
- Chance of exploitation in the next 30 days. Higher than 61.88% of scored vulnerabilities.
- Known exploited
- No
- Not in CISA's catalog
- Weakness
- CWE-770 Allocation of Resources Without Limits or Throttling
- Fix
10.0.13- Upgrade System.Security.Cryptography.Xml to this version or later
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/489
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-770 (Allocation of Resources Without Limits or Throttling)
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, you're 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. 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.
- 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 --infocommand.
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
Acknowledgements
- novice-22
- Ky0toFu (@ky0tofu)
- Dr.-Ing Ashar Javed (@soaj1664ashar)
Revisions
V1.0 (10/13/2026): Advisory published.
Affected versions
NuGet
| Package | Vulnerable | Fixed in |
|---|---|---|
| System.Security.Cryptography.Xml | >= 10.0.0, < 10.0.13 |
10.0.13 |
| System.Security.Cryptography.Xml | >= 11.0.0-preview.1, < 11.0.0-rc.2 |
11.0.0-rc.2 |
| System.Security.Cryptography.Xml | >= 8.0.0, < 8.0.5 |
8.0.5 |
| System.Security.Cryptography.Xml | >= 9.0.0, < 9.0.21 |
9.0.21 |
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.
System.Security.Cryptography.Xml NuGet → 10.0.13
- dotnet
dotnet add package System.Security.Cryptography.Xml --version 10.0.13
Severity breakdown
CVSS 3.1 7.5
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
Weakness
CWE-770: Allocation of Resources Without Limits or Throttling
The product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated.
How to prevent it
- Requirements: Clearly specify the minimum and maximum expectations for capabilities, and dictate which behaviors are acceptable when resource allocation reaches limits.
- Architecture and Design: Limit the amount of resources that are accessible to unprivileged users. Set per-user limits for resources. Allow the system administrator to define these limits. Be careful to avoid CWE-410.
- Architecture and Design: Design throttling mechanisms into the system architecture. The best protection is to limit the amount of resources that an unauthorized user can cause to be expended. A strong authentication and access control model will help prevent such attacks from occurring in the first place, and it will help the administrator to identify who is committing the abuse. The login application should be protected against DoS attacks as much as possible. Limiting the database access, perhaps by caching result sets, can help minimize the resources expended. To further limit the potential for a DoS attack, consider tracking the rate of requests received from users and blocking requests that exceed a defined rate threshold.
- 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.
- Architecture and Design: Mitigation of resource exhaustion attacks requires that the target system either: recognizes the attack and denies that user further access for a given amount of time, typically by using increasing time delays uniformly throttles all requests in order to make it more difficult to consume resources more quickly than they can again be freed. The first of these solutions is an issue in itself though, since it may allow attackers to prevent the use of the system by a particular valid user. If the attacker impersonates the valid user, they may be able to prevent the user from accessing the server in question. The second solution can be difficult to effectively institute -- and even when properly done, it does not provide a full solution. It simply requires more resources on the part of the attacker.
- Architecture and Design: Ensure that protocols have specific limits of scale placed on them.
- Architecture and Design, Implementation: If the program must fail, ensure that it fails gracefully (fails closed). There may be a temptation to simply let the program fail poorly in cases such as low memory conditions, but an attacker may be able to assert control before the software has fully exited. Alternately, an uncontrolled failure could cause cascading problems with other downstream components; for example, the program could send a signal to a downstream process so the process immediately knows that a problem has occurred and has a better chance of recovery. Ensure that all failures in resource allocation place the system into a safe posture.
- Operation, Architecture and Design: Use quotas or other resource-limiting settings provided by the operating system or environment. For example, when managing system resources in POSIX, setrlimit() can be used to set limits for certain types of resources, and getrlimit() can determine how many resources are available. However, these functions are not available on all operating systems. When the current levels get close to the maximum that is defined for the application (see CWE-770), then limit the allocation of further resources to privileged users; alternately, begin releasing resources for less-privileged users. While this mitigation may protect the system from attack, it will not necessarily stop attackers from adversely impacting other users. Ensure that the application performs the appropriate error checks and error handling in case resources become unavailable (CWE-703).
References
Advisories
Packages
Other links
Timeline
- Published
- Last updated by the source
- Latest EPSS score
Related advisories
| Advisory | Severity | Why it's related |
|---|---|---|
| GHSA-7hqp-7c5m-4vq6 Microsoft Security Advisory CVE-2026-96960 - .NET and Visual Studio Denial of Service Vulnerability | High | Also affects System.Security.Cryptography.Xml |
| GHSA-r955-8q5j-3h83 Microsoft Security Advisory CVE-2026-96958 - .NET and Visual Studio Denial of Service Vulnerability | High | Also affects System.Security.Cryptography.Xml |
| GHSA-vrv5-2jg9-4mmr Microsoft Security Advisory CVE-2026-96222 - .NET Spoofing Vulnerability | High | Also affects System.Security.Cryptography.Xml |
| GHSA-23rf-6693-g89p Microsoft Security Advisory CVE-2026-50648 – .NET Denial of Service Vulnerability | High | Also affects System.Security.Cryptography.Xml |
| GHSA-mmjf-rqrv-855v Microsoft Security Advisory CVE-2026-50527 – .NET Denial of Service Vulnerability | High | Also affects System.Security.Cryptography.Xml |
| GHSA-8q5v-6pqq-x66h Microsoft Security Advisory CVE-2026-50525 – .NET Denial of Service Vulnerability | High | Also affects System.Security.Cryptography.Xml |
| GHSA-g8r8-53c2-pm3f Microsoft Security Advisory CVE-2026-47304 – .NET Security Feature Bypass Vulnerability | Critical | Also affects System.Security.Cryptography.Xml |
| GHSA-cvvh-rhrc-wg4q Microsoft Security Advisory CVE-2026-47302 – .NET Denial of Service Vulnerability | High | Also affects System.Security.Cryptography.Xml |
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