CVE-2026-96222: Microsoft Security Advisory CVE-2026-96222 - .NET Spoofing Vulnerability in nuget Package System.Security.Cryptography.Xml
A high-severity advisory for the nuget package System.Security.Cryptography.Xml is fixed in version 8.0.5.
Key points
- System.Security.Cryptography.Xml (nuget) has a high flaw.
- Tracked as CVE-2026-96222.
- Version 8.0.5.
Maintainers of System.Security.Cryptography.Xml, a package in the nuget ecosystem, have published a high-severity security advisory (CVE-2026-96222): Microsoft Security Advisory CVE-2026-96222 - .NET Spoofing Vulnerability.
At a glance
- Advisory
- GHSA-vrv5-2jg9-4mmr
- CVE
- CVE-2026-96222
- Package
- System.Security.Cryptography.Xml (nuget)
- Severity
- High
- Patched in
- 8.0.5
What is the issue?
The GitHub-reviewed advisory explains: Executive summary Microsoft is releasing this security advisory to provide information about a vulnerability in System.Security.Cryptography.Xml. This advisory also provides guidance on what developers can do to update their applications to remove this vulnerability. KeyInfoX509Data can accept serialized certificate formats containing attacker-controlled chain metadata instead of requiring a plain X.509 certificate, contributing to certificate-forgery and token-spoofing paths. Announcement Announcement for this issue can be found at https://github.com/dotnet/announcements/issues/474 CVSS Details - Version: 3.1 - Severity: High - Score: 7.4 - Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N - Weakness: CWE-295 (Improper Certificate Validation) Affected Platforms - Platforms: Windows, Linux, macOS - Architectures: All <a name="affected-packages"</aAffected Packages The vulnerability af
Affected versions
| Ecosystem | Package | Vulnerable | Patched |
|---|---|---|---|
| nuget | System.Security.Cryptography.Xml | >= 8.0.0, <= 8.0.4 | 8.0.5 |
The advisory lists a CVSS score of 7.4.
How to fix it
- Upgrade the affected package to the first patched version listed above.
- Rebuild and redeploy applications that bundle the vulnerable dependency.
- Run your dependency scanner (npm audit, pip-audit, Dependabot) to find transitive uses.
- Review the advisory references for workaround details if you cannot upgrade yet.
What to do and how to stay safe: CVE-2026-96222
- Vulnerability severity scores ignore your specific architecture and context.
- Exploitability depends on network exposure and user behavior, not just code flaws.
- Prioritization requires continuous asset inventory and threat intelligence alignment.
Risk-based vulnerability management focuses your limited resources on the flaws that actually threaten your business. Start by mapping your critical assets and checking for active exploits to prioritize your backlog.
Step-by-step guide: Risk-Based Vulnerability Management: Prioritize Fixes by Actual Danger
General security guidance from the Threat Times newsroom. It is not confirmed advice from the organisations named in this story.
Frequently asked questions
What is CVE-2026-96222?
CVE-2026-96222 is a security vulnerability in System.Security.Cryptography.Xml (nuget).
Which version fixes CVE-2026-96222?
The fix is in version 8.0.5.
