CVE Intelligence
High Cryptography

CVE-2026-96222 — Active Directory Federation Services (AD FS) Spoofing Vulnerability

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

Published Oct 13, 2026 · Updated Oct 13, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP, GitHub Security Advisories · CNA: microsoft

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.
How the score was calculated
  • EPSS 0.6% (30-day exploitation probability)+7
  • Technical severity (high)+6

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation
Not confirmed
Not in CISA KEV — an absence of record, not proof it is unexploited.
EPSS FIRST
0.58%
ahead of 47% of scored CVEs · Oct 14, 2026
Affects
Microsoft
Microsoft .NET Framework 3.5 and 21 more
CVSS base
7.4
High · 3 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation
None
none · proof-of-concept · active
Automatable
No
can an attacker script the kill-chain steps
Technical impact
Total
partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

  • Nuget System.Security.Cryptography.Xml: fixed in version 8.0.5 — github.com (GitHub Security Advisories)

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

  1. Identify exposed assets running the affected vendor/product/version combinations (Microsoft Microsoft .NET Framework 3.5, Microsoft Microsoft .NET Framework 3.5 AND 4.6.2/4.7/4.7.1/4.7.2, Microsoft Microsoft .NET Framework 3.5 AND 4.7.2…).
  2. The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
  3. Apply the fixed version or the patch documented under Remediation.
  4. Search available logs for exploit probes matching the vulnerability class (cryptography), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

VendorProductVersionsStatusSource
Microsoft Microsoft .NET Framework 3.5 ≥ 3.5.0 and < 2.0.50727.9188 AND 3.0.30729.9171 Vulnerable CVE Program (cve.org) e CISA ADP
Microsoft Microsoft .NET Framework 3.5 AND 4.6.2/4.7/4.7.1/4.7.2 ≥ 3.0.0.0 and < 2.0.50727.8987 AND 3.0.30729.8982 AND 4.7.4150.0 Vulnerable CVE Program (cve.org) e CISA ADP
Microsoft Microsoft .NET Framework 3.5 AND 4.7.2 ≥ 4.7.0 and < 2.0.50727.9073 AND 3.0.30729.9070 AND 4.7.4150.0 Vulnerable CVE Program (cve.org) e CISA ADP
Microsoft Microsoft .NET Framework 3.5 AND 4.8 ≥ 4.8.0 and < 2.0.50727.9073 AND 3.0.30729.9070 AND 4.8.4811.0 Vulnerable CVE Program (cve.org) e CISA ADP
Microsoft Microsoft .NET Framework 3.5 AND 4.8.1 ≥ 4.8.1 and < 2.0.50727.9188 AND 3.0.30729.9171 AND 4.8.9363.0 Vulnerable CVE Program (cve.org) e CISA ADP
Microsoft Microsoft .NET Framework 4.6.2/4.7/4.7.1/4.7.2 ≥ 4.7.0 and < 4.7.4150.0 Vulnerable CVE Program (cve.org) e CISA ADP
Microsoft Microsoft .NET Framework 4.8 ≥ 4.8.0 and < 4.8.4811.0 Vulnerable CVE Program (cve.org) e CISA ADP
Microsoft Microsoft .NET Framework 4.8.1 ≥ 4.8.0.0 and < 4.8.9363.0 Vulnerable CVE Program (cve.org) e CISA ADP
Microsoft Microsoft Visual Studio 2022 version 17.14 ≥ 17.14.0 and < 17.14.42 Vulnerable CVE Program (cve.org) e CISA ADP
Microsoft Microsoft Visual Studio 2026 version 18.10 ≥ 18.10.0 and < 18.10.4 Vulnerable CVE Program (cve.org) e CISA ADP
Microsoft System.Security.Cryptography.Xml ≥ 10.0.0 and < 8.0.5 Vulnerable CVE Program (cve.org) e CISA ADP
Microsoft Windows 10 Version 1607 ≥ 10.0.14393.0 and < 10.0.14393.9612 Vulnerable CVE Program (cve.org) e CISA ADP
Microsoft Windows 10 Version 1809 ≥ 10.0.17763.0 and < 10.0.17763.9376 Vulnerable CVE Program (cve.org) e CISA ADP
Microsoft Windows Server 2012 R2 ≥ 6.3.9600.0 and < 6.3.9600.23470 Vulnerable CVE Program (cve.org) e CISA ADP
Microsoft Windows Server 2012 R2 (Server Core installation) ≥ 6.3.9600.0 and < 6.3.9600.23470 Vulnerable CVE Program (cve.org) e CISA ADP
Microsoft Windows Server 2016 ≥ 10.0.14393.0 and < 10.0.14393.9612 Vulnerable CVE Program (cve.org) e CISA ADP
Microsoft Windows Server 2016 (Server Core installation) ≥ 10.0.14393.0 and < 10.0.14393.9612 Vulnerable CVE Program (cve.org) e CISA ADP
Microsoft Windows Server 2019 ≥ 10.0.17763.0 and < 10.0.17763.9376 Vulnerable CVE Program (cve.org) e CISA ADP
Microsoft Windows Server 2019 (Server Core installation) ≥ 10.0.17763.0 and < 10.0.17763.9376 Vulnerable CVE Program (cve.org) e CISA ADP
Microsoft Windows Server 2022 ≥ 10.0.20348.0 and < 10.0.20348.5761 Vulnerable CVE Program (cve.org) e CISA ADP
Microsoft Windows Server 2025 ≥ 10.0.26100.0 and < 10.0.26100.33650 Vulnerable CVE Program (cve.org) e CISA ADP
Microsoft Windows Server 2025 (Server Core installation) ≥ 10.0.26100.0 and < 10.0.26100.33650 Vulnerable CVE Program (cve.org) e CISA ADP
Nuget System.Security.Cryptography.Xml ≥ 8.0.0 and ≤ 8.0.4 Vulnerable GitHub Security Advisories

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector
Network
Attack complexity
High
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

ScoreVersionSeverityExpl.ImpactScored by
7.4 CVSS 3.1 High 2.2 5.2 secure@microsoft.com via NIST National Vulnerability Database
7.4 CVSS 3.1 High — — GitHub, Inc. via GitHub Security Advisories
7.4 CVSS 3.1 High — — microsoft via CVE Program (cve.org) e CISA ADP
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N (score shown at the top: secure@microsoft.com)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-295 · Improper Certificate Validation

Other CVEs with this weakness →

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

  • Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
  • Check TLS negotiations and unexpected certificates in the component’s traffic.
web/proxy/WAF logsnetwork IDS/IPS

Timeline

What happened to this CVE, newest first.

  • 2026
  • SSVC assessment updated
    Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
  • Fix documented
    Oct 13, 2026 · GitHub Security Advisories
  • Affected products added · nuget/system.security.cryptography.xml
    Oct 13, 2026 · GitHub Security Advisories
  • Affected products added · microsoft/microsoft .net framework 3.5, microsoft/microsoft .net framework 3.5 and 4.6.2/4.7/4.7.1/4.7.2, microsoft/micr
    Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
  • Record published
    Oct 13, 2026
  • CVSS changed · 7.4
    Oct 13, 2026 · NIST National Vulnerability Database
  • Source status changed · → Awaiting Analysis
    Oct 13, 2026 · NIST National Vulnerability Database
  • Record created in this database
    Oct 13, 2026 · NIST National Vulnerability Database
  • CVE published
    Oct 13, 2026 · microsoft

Source activity

Repeated readings are counted rather than listed.

  • 1× References added · Oct 13, 2026 – Oct 13, 2026
  • 1× Official description updated · Oct 13, 2026 – Oct 13, 2026

References

5 on the record

Elsewhere on this site

Microsoft
every CVE for this vendor
Cryptography
same class
CWE-295
other pages naming this weakness

Related CVEs (same products)

  • CVE-2026-109468 ASP.NET Core Denial of Service Vulnerability 3h
  • CVE-2026-97844 Role: DNS Server Information Disclosure Vulnerability 2d
  • CVE-2026-97839 Role: DNS Server Information Disclosure Vulnerability 2d
  • CVE-2026-97840 Role: DNS Server Information Disclosure Vulnerability 2d
  • CVE-2026-97841 Role: DNS Server Information Disclosure Vulnerability 2d
  • CVE-2026-97842 Role: DNS Server Information Disclosure Vulnerability 2d

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

  • No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
  • No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
  • No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-96222 is "Active Directory Federation Services (AD FS) Spoofing Vulnerability", rated High. It affects Microsoft .NET Framework 3.5 (Microsoft); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 7.4 describes technical severity. EPSS 0.58% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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