CVE-2026-96222: Microsoft .NET certificate validation bypass in Cryptography.Xml

CVE-2026-96222 · Severity: high · CVSS 7.4 · Published 2026-10-13

A vulnerability in Microsoft .NET's System.Security.Cryptography.Xml component allows attackers to forge or spoof cryptographic tokens by accepting tampered certificate chain metadata. An attacker exploiting this could impersonate legitimate entities, bypass authentication, or forge digital signatures without access to the private key, potentially leading to unauthorized access or data compromise.

Technologies: Microsoft System.Security.Cryptography.Xml, System.Security.Cryptography.Xml (NuGet). Vendors: Microsoft, NuGet.

Quick answers

Is CVE-2026-96222 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-96222 being exploited in the wild.
How severe is CVE-2026-96222?
High severity, with a CVSS score of 7.4, published 13 October 2026.
Which products and versions are affected?
Microsoft System.Security.Cryptography.Xml 8.0.0 through 8.0.4; System.Security.Cryptography.Xml (NuGet) >= 8.0.0, <= 8.0.4, ECOSYSTEM:introduced=8.0.0,fixed=8.0.5.
Is there a fix for CVE-2026-96222?
Yes. System.Security.Cryptography.Xml (NuGet): upgrade to 8.0.5 or later. Until then: Update System.Security.Cryptography.Xml to version 8.0.5 or later. If using self-contained applications targeting affected versions, recompile and redeploy with the patched library. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-96222 attacked?
It is attacked over the network.
Am I affected by CVE-2026-96222?
Check whether you run 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 8.0.5 or later
    dotnet add package System.Security.Cryptography.Xml --version 8.0.5

Update System.Security.Cryptography.Xml to version 8.0.5 or later. If using self-contained applications targeting affected versions, recompile and redeploy with the patched library.

Technical details

KeyInfoX509Data in System.Security.Cryptography.Xml improperly validates X.509 certificates, accepting serialized formats with attacker-controlled chain metadata instead of requiring plaintext X.509 certificates (CWE-295). The vulnerability affects versions 8.0.0 through 8.0.4 and requires network access but no authentication or user interaction. An attacker can forge certificates or spoof security tokens. A patch exists in version 8.0.5.

Affected products

  • Microsoft System.Security.Cryptography.Xml 8.0.0 through 8.0.4

Identifiers

  • CVE-2026-96222
  • GHSA-vrv5-2jg9-4mmr

Timeline

  • 2026-10-13: disclosed: Advisory published by Microsoft
  • 2026-10-13: patched: Patch released in System.Security.Cryptography.Xml 8.0.5

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