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CVE-2026-85321

Windows Server 2012 R2: Active Directory Federation Services (AD FS) Denial of Service Vulnerability

Microsoft Windows Server 2012 R2Operating systems
Open in ThreatlineRecord JSON
CVSS
7.5High
ExploitationNo known exploitationNot in CISA KEV, which does not prove it is unexploitedCISA KEV
Exploit odds (EPSS)1.06%Chance of exploitation activity in the next 30 days, higher than 64% of CVEs. Scored 23 Oct 2026FIRST EPSS
Fixed in6.3.9600.23470Also 10.0.14393.9612, 10.0.17763.9376 and 2 moreCVE List
Published13 Oct 2026Updated 23 Oct 2026CVE List

What fixes it

  • 6.3.9600.23470Windows Server 2012 R2CVE List
  • 6.3.9600.23470Windows Server 2012 R2 (Server Core installation)CVE List
  • 10.0.14393.9612Windows Server 2016CVE List
  • 10.0.14393.9612Windows Server 2016 (Server Core installation)CVE List
  • 10.0.17763.9376Windows Server 2019CVE List
  • 10.0.17763.9376Windows Server 2019 (Server Core installation)CVE List
Show all 9 fixed versions
  • 10.0.20348.5761Windows Server 2022CVE List
  • 10.0.26100.33650Windows Server 2025CVE List
  • 10.0.26100.33650Windows Server 2025 (Server Core installation)CVE List

A fixed version on one release line is not the upgrade target for every line. Check your exact version and any vendor backports.

Vendor and government advisories 1

Vendors that say their products are affected, and agencies that issued alerts. Check each for the fixed release of the product you run.

Reports 1

1 outlet mention it. Reports are not confirmation; each links to its source.

Description

Allocation of resources without limits or throttling in Active Directory Federation Services (AD FS) allows an unauthorized attacker to deny service over a network.

Text from CVE List

Affected versions 9

  • Windows Server 2012 R2affected: 6.3.9600.0 before 6.3.9600.23470CVE List
  • Windows Server 2012 R2 (Server Core installation)affected: 6.3.9600.0 before 6.3.9600.23470CVE List
  • Windows Server 2016affected: 10.0.14393.0 before 10.0.14393.9612CVE List
  • Windows Server 2016 (Server Core installation)affected: 10.0.14393.0 before 10.0.14393.9612CVE List
  • Windows Server 2019affected: 10.0.17763.0 before 10.0.17763.9376CVE List
  • Windows Server 2019 (Server Core installation)affected: 10.0.17763.0 before 10.0.17763.9376CVE List
  • Windows Server 2022affected: 10.0.20348.0 before 10.0.20348.5761CVE List
  • Windows Server 2025affected: 10.0.26100.0 before 10.0.26100.33650CVE List
  • Windows Server 2025 (Server Core installation)affected: 10.0.26100.0 before 10.0.26100.33650CVE List

References 1