---
id: CVE-2026-96222
title: >-
  Improper certificate validation in Active Directory Federation Services (AD
  FS) allows an unauthorized attacker to perform spoofing over a network.
summary: >-
  Improper certificate validation in Active Directory Federation Services (AD
  FS) allows an unauthorized attacker to perform spoofing over a network.
severity: high
cvss: 7.4
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N'
cwe:
  - CWE-295
vendor: System
product: System.Security.Cryptography.Xml
affected:
  - 'System.Security.Cryptography.Xml >= 8.0.0, <= 8.0.4'
patched:
  - System.Security.Cryptography.Xml 8.0.5
published: '2026-10-13'
updated: '2026-10-14'
sourceUpdated: '2026-10-14T04:18:57.730'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-96222'
references:
  - url: 'https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-96222'
    label: secure@microsoft.com
  - url: 'https://github.com/dotnet/runtime/security/advisories/GHSA-vrv5-2jg9-4mmr'
  - url: 'https://github.com/dotnet/announcements/issues/474'
  - url: 'https://github.com/dotnet/runtime/issues/135705'
  - url: 'https://github.com/advisories/GHSA-vrv5-2jg9-4mmr'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-96222'
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-96222.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-96222'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2548802'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-96222'
  - url: 'https://access.redhat.com/errata/RHSA-2026:86168'
  - url: 'https://access.redhat.com/errata/RHSA-2026:86594'
  - url: 'https://access.redhat.com/errata/RHSA-2026:86169'
  - url: 'https://access.redhat.com/errata/RHSA-2026:84693'
  - url: 'https://access.redhat.com/errata/RHSA-2026:88474'
  - url: 'https://access.redhat.com/errata/RHSA-2026:88425'
  - url: 'https://access.redhat.com/errata/RHSA-2026:88422'
tags:
  - nvd
  - ghsa
  - nuget
  - cve.org
  - csaf
  - vex
  - red-hat
aliases:
  - GHSA-vrv5-2jg9-4mmr
ecosystem: nuget
ingestedAt: '2026-10-13T19:43:29.252Z'
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-10-08T00:00:00+00:00'
epss: 0.00586
epssPercentile: 0.47839
---

## Overview

Improper certificate validation in Active Directory Federation Services (AD FS) allows an unauthorized attacker to perform spoofing over a network.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Package advisory (CVE-2026-96222)

Affected packages:

- `System.Security.Cryptography.Xml >= 8.0.0, <= 8.0.4`

Patched in:

- `System.Security.Cryptography.Xml 8.0.5`

Source: https://github.com/advisories/GHSA-vrv5-2jg9-4mmr

## Vendor advisories

- **RHSA-2026:86168** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 10), Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) · released 2026-10-20 · [advisory](https://access.redhat.com/errata/RHSA-2026:86168)
- **RHSA-2026:86594** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 8), Red Hat Enterprise Linux CRB (v. 8) · released 2026-10-21 · [advisory](https://access.redhat.com/errata/RHSA-2026:86594)
- **RHSA-2026:86169** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 9), Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) · released 2026-10-20 · [advisory](https://access.redhat.com/errata/RHSA-2026:86169)
- **RHSA-2026:84693** · Red Hat · fixed in: Red Hat Hardened Images · released 2026-10-19 · [advisory](https://access.redhat.com/errata/RHSA-2026:84693)
- **RHSA-2026:88474** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream EUS (v. 10.0), Red Hat Enterprise Linux CodeReady Linux Builder EUS (v. 10.0) · released 2026-10-22 · [advisory](https://access.redhat.com/errata/RHSA-2026:88474)
- **RHSA-2026:88425** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream E4S (v.9.4) · released 2026-10-22 · [advisory](https://access.redhat.com/errata/RHSA-2026:88425)
- **RHSA-2026:88422** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream EUS (v.9.6), Red Hat CodeReady Linux Builder EUS (v.9.6) · released 2026-10-22 · [advisory](https://access.redhat.com/errata/RHSA-2026:88422)