Hazard

Is CVE-2026-56155 being exploited?

Confirmed exploited in the wild

CISA has evidence of active exploitation. This is not theoretical risk — someone has already used it against someone.

Microsoft Active Directory Federation Services Insufficient Granularity of Access Control Vulnerability

Microsoft · Active Directory Federation Services

CVSS 7.8 EPSS 2% no public exploit indexed Fix deadline passed 28 July 2026

What it is

Microsoft Active Directory Federation Services contains an insufficient granularity of access control vulnerability that allows an authorized attacker to elevate privileges locally.

Why we say that

  • CISA's federal remediation deadline (2026-07-28) has passed
  • Listed in the CISA Known Exploited Vulnerabilities catalogue

Every line above comes from a named public source. Where the evidence is thin, we say so rather than inventing confidence — see methodology.

What to do

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.

What it costs when this goes wrong

This is where UK enforcement meets the vulnerability record. Where an unfixed vulnerability leads to a breach, the ICO treats it as a security failure under UK GDPR. Recent cases:

All UK cases caused by unpatched software →