# CVE-2026-96958: Inefficient algorithmic complexity in .NET allows an unauthorized attacker to deny service over a network.

Source: https://junglewise.ai/threats/cve-2026-96958-microsoft-security-advisory-net-and-visual-studio-denial-of  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-13. Updated: 2026-10-13  
License: CC BY 4.0 with a link back

CVE-2026-96958 · Severity: high · CVSS 7.5 · Published 2026-10-13

Microsoft's XML cryptography library has a flaw that allows attackers to cause a denial of service by crafting specially-formed signed XML documents that consume excessive CPU resources. Applications that process untrusted XML signatures are vulnerable to outages when handling these malicious inputs.

Technologies: [Microsoft System.Security.Cryptography.Xml](https://junglewise.ai/threats/technologies/microsoft-system-security-cryptography-xml), [System.Security.Cryptography.Xml (NuGet)](https://junglewise.ai/threats/technologies/system-security-cryptography-xml). Vendors: [Microsoft](https://junglewise.ai/threats/vendors/microsoft), [NuGet](https://junglewise.ai/threats/vendors/nuget).

## Quick answers

**Is CVE-2026-96958 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-96958 being exploited in the wild.

**How severe is CVE-2026-96958?** High severity, with a CVSS score of 7.5, published 13 October 2026.

**Which products and versions are affected?** Microsoft System.Private.Xml affected in .NET runtimes; Microsoft System.Security.Cryptography.Xml 8.0.0-8.0.4, 9.0.0-9.0.20, 10.0.0-10.0.12, 11.0.0-preview.1 through 11.0.0-rc.1; System.Security.Cryptography.Xml (NuGet) >= 10.0.0, <= 10.0.12, ECOSYSTEM:introduced=10.0.0,fixed=10.0.13.

**Is there a fix for CVE-2026-96958?** Yes. System.Security.Cryptography.Xml (NuGet): upgrade to 10.0.13 or later. Until then: Install the latest .NET SDK or runtime version, or update the System.Security.Cryptography.Xml package reference to the patched version. Applications deployed as self-contained deployments must be recompiled and redeployed with the fixed package versions. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-96958 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-96958?** Check whether you run Microsoft System.Private.Xml, Microsoft System.Security.Cryptography.Xml or System.Security.Cryptography.Xml (NuGet) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- System.Security.Cryptography.Xml (NuGet): upgrade to 10.0.13 or later

  ```sh
  dotnet add package System.Security.Cryptography.Xml --version 10.0.13
  ```


Install the latest .NET SDK or runtime version, or update the System.Security.Cryptography.Xml package reference to the patched version. Applications deployed as self-contained deployments must be recompiled and redeployed with the fixed package versions.

## Technical details

The System.Security.Cryptography.Xml and System.Private.Xml libraries suffer from inefficient algorithmic complexity (CWE-407) in signed XML processing. An attacker can send a malicious XML document with excessive nesting depth, operation counts, or entity references that causes the parser to consume unbounded CPU and memory, leading to denial of service. Network-accessible .NET applications processing untrusted XML are vulnerable without authentication or user interaction required.

## Affected products

- Microsoft System.Security.Cryptography.Xml 8.0.0-8.0.4, 9.0.0-9.0.20, 10.0.0-10.0.12, 11.0.0-preview.1 through 11.0.0-rc.1
- Microsoft System.Private.Xml affected in .NET runtimes

## Identifiers

- CVE-2026-96958
- GHSA-r955-8q5j-3h83

## Timeline

- 2026-10-13: advisory

## Related threats

- [Microsoft .NET certificate validation bypass in Cryptography.Xml](https://junglewise.ai/threats/cve-2026-96222-microsoft-security-advisory-net-spoofing-vulnerability)
- [Asymmetric resource consumption (amplification) in .NET allows an unauthorized attacker to deny service over a network.](https://junglewise.ai/threats/cve-2026-96960-microsoft-security-advisory-net-and-visual-studio-denial-of)
- [Allocation of resources without limits or throttling in .NET allows an unauthorized attacker to deny service over a network.](https://junglewise.ai/threats/cve-2026-96959-microsoft-security-advisory-net-and-visual-studio-denial-of)
- [Microsoft .NET Framework denial of service via resource exhaustion](https://junglewise.ai/threats/cve-2026-50648-microsoft-net-framework-denial-of-service-via-resource-exhaustion)
- [Microsoft .NET Framework stack-based buffer overflow](https://junglewise.ai/threats/cve-2026-50527-microsoft-net-framework-stack-based-buffer-overflow)