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CVE-2026-56155

Microsoft Active Directory Federation Services Insufficient Granularity of Access Control Vulnerability

7.8 HIGHActively exploited (CISA KEV)EPSS 0.35%
  1. Published14 Jul 2026
  2. Added to CISA KEV14 Jul 2026
  3. Remediation due28 Jul 2026
Actively exploited (CISA KEV)

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

Added to KEV: 14 Jul 2026Federal remediation due: 28 Jul 2026

Description

Insufficient granularity of access control in Active Directory Federation Services (AD FS) allows an authorized attacker to elevate privileges locally.

CVSS 3.1 breakdown

Attack vectorLocal
Attack complexityLow
Privileges requiredLow
User interactionNone
ScopeUnchanged
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected products

Microsoft Windows 10 1607< 10.0.14393.9339
Microsoft Windows 10 1809< 10.0.17763.9020
Microsoft Windows Server 2012r2
Microsoft Windows Server 2016< 10.0.14393.9339
Microsoft Windows Server 2019< 10.0.17763.9020
Microsoft Windows Server 2022< 10.0.20348.5386
Microsoft Windows Server 2025< 10.0.26100.33158

Remediation

Fixed in
Microsoft Windows 10 1607≥ 10.0.14393.9339
Microsoft Windows 10 1809≥ 10.0.17763.9020
Microsoft Windows Server 2016≥ 10.0.14393.9339
Microsoft Windows Server 2019≥ 10.0.17763.9020
Microsoft Windows Server 2022≥ 10.0.20348.5386
Microsoft Windows Server 2025≥ 10.0.26100.33158

References

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Frequently asked

Is CVE-2026-56155 being actively exploited?

Yes. CVE-2026-56155 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, added 14 Jul 2026.

How severe is CVE-2026-56155?

CVE-2026-56155 has a CVSS 3.1 base score of 7.8, rated high. EPSS estimates a 0.35% probability of exploitation.

Which products are affected by CVE-2026-56155?

Affected products include Microsoft Windows 10 1607, Microsoft Windows 10 1809, Microsoft Windows Server 2012, Microsoft Windows Server 2016, Microsoft Windows Server 2019, and 2 more.

How do I fix CVE-2026-56155?

Upgrade affected software to a fixed version, for example Microsoft Windows 10 1607 10.0.14393.9339, Microsoft Windows 10 1809 10.0.17763.9020, Microsoft Windows Server 2016 10.0.14393.9339 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2026-56155 against the real software inventory on every managed device, as each hourly inventory arrives. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. Because it is on the CISA KEV list, a risk for it never ranks below high, and the update that fixes it moves to the Emergency patch lane. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

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Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.