Active Directory Federation Services: zero-day EoP

Active Directory administrators should note the emergence today of CVE-2026-56155, an exploited-in-the-wild elevation of privilege vulnerability in Active Directory Federation Services which allows an authorized attacker to elevate privileges locally. Eight other vulnerabilities are also published today in Active Directory Federation Services, all ranked as Important on Microsoft’s proprietary severity ranking scale. The advisory doesn’t explicitly describe the location of the attacker, but it’s likely that an attacker would need an existing toehold on the target system to chain together with the elevation of privilege opportunity on offer here.