Microsoft Active Directory Federation Services Insufficient Granularity of Access Control Vulnerability
Insufficient granularity of access control in Active Directory Federation Services (AD FS) allows an authorized attacker to elevate privileges locally.
What happened
Insufficient granularity of access control in Active Directory Federation Services (AD FS) allows an authorized attacker to elevate privileges locally.
CISA lists it as exploited, added 14 Jul 2026.
Does it affect you
Names Microsoft Windows Server. Enter the product and version you run to place it against the affected range the vendor published.
What to do
- Follow the vendor advisory for the fixed release and any interim mitigation.
msrc.microsoft.com - Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.
cisa.gov
CISA’s notes for this entry:
- msrc.microsoft.com/update-guide/en-US/vulnerability/CVE-2026-56155
- BOD 26-04: cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk
- Forensics Triage Requirements: cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk
- nvd.nist.gov/vuln/detail/CVE-2026-56155
- learn.microsoft.com/en-us/windows-server/identity/ad-fs/decommission/adfs-decommission-guide
Affected, as published to NVD
- ms-winserver
- Microsoft Windows Server: everything below 10.0.14393.9339
The record
- NVD status
- Analyzed
- Published
- 14 Jul 2026, last modified 15 Jul 2026 (NVD)
- Severity
- CVSS 3.1 base score 7.8, High — computed here from the vector; NVD states 7.8.
- Vector
- CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- Weakness
- CWE-1220 (NVD; names by MITRE)
- Exploitation
- Listed in CISA’s Known Exploited Vulnerabilities catalogue since 14 Jul 2026; federal remediation due 28 Jul 2026. CISA entry
- Exploit probability
- EPSS 0.3%, 27th percentile — FIRST, scored 23 Oct 2026. FIRST EPSS
- Vendor
- Microsoft · Active Directory Federation Services (CISA)
References on the NVD record
- msrc.microsoft.com/update-guide/vulnerability/CVE-2026-56155Vendor Advisory
- cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-56155US Government Resource
Sources
The verdict above is computed from the products and versions you entered and the affected ranges the vendor published to NVD. It does not inspect your environment, and this site never reports a product as unaffected: why.