CVE-2026-56155

Published Jul 14, 2026

Last updated a month ago

Exploit known CVSS high 7.8

Cloud

Network

Zero-day

Server

Overview

AI description

Automated description summarized from trusted sources.

CVE-2026-56155 is an elevation of privilege vulnerability found in Microsoft Active Directory Federation Services (AD FS). This flaw stems from an insufficient granularity of access control within the service. An authorized attacker can exploit this vulnerability to locally elevate their privileges. Microsoft has addressed this issue, noting that it was actively exploited in the wild as a zero-day vulnerability. Organizations are advised to apply mitigations in accordance with vendor instructions to address this vulnerability.

Description: Insufficient granularity of access control in Active Directory Federation Services (AD FS) allows an authorized attacker to elevate privileges locally.
Source: secure@microsoft.com
NVD status: Analyzed
Products: windows_10_1607, windows_10_1809, windows_server_2012, windows_server_2016, windows_server_2019, windows_server_2022, windows_server_2025

Risk scores

CVSS 3.1

Type: Secondary
Base score: 7.8
Impact score: 5.9
Exploitability score: 1.8
Vector string: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Severity: HIGH

Known exploits

Data from CISA

Vulnerability name: Microsoft Active Directory Federation Services Insufficient Granularity of Access Control Vulnerability
Exploit added on: Jul 14, 2026
Exploit action due: Jul 28, 2026
Required action: 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.

Weaknesses

secure@microsoft.com: CWE-1220

Hype score: Not currently trending

Configurations

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  {
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      {
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            "versionEndExcluding": "10.0.14393.9339",
            "vulnerable": true
          },
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            "matchCriteriaId": "A9DC4EC9-4E72-4CBC-BA0B-39CCC45DB8CE",
            "versionEndExcluding": "10.0.14393.9339",
            "vulnerable": true
          },
          {
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            "versionEndExcluding": "10.0.17763.9020",
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          },
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            "versionEndExcluding": "10.0.17763.9020",
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          },
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            "criteria": "cpe:2.3:o:microsoft:windows_server_2012:-:*:*:*:*:*:*:*",
            "matchCriteriaId": "A7DF96F8-BA6A-4780-9CA3-F719B3F81074",
            "vulnerable": true
          },
          {
            "criteria": "cpe:2.3:o:microsoft:windows_server_2012:r2:*:*:*:*:*:*:*",
            "matchCriteriaId": "DB18C4CE-5917-401E-ACF7-2747084FD36E",
            "vulnerable": true
          },
          {
            "criteria": "cpe:2.3:o:microsoft:windows_server_2016:*:*:*:*:*:*:*:*",
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            "versionEndExcluding": "10.0.14393.9339",
            "vulnerable": true
          },
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            "criteria": "cpe:2.3:o:microsoft:windows_server_2019:*:*:*:*:*:*:*:*",
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            "versionEndExcluding": "10.0.17763.9020",
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          },
          {
            "criteria": "cpe:2.3:o:microsoft:windows_server_2022:*:*:*:*:*:*:*:*",
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            "versionEndExcluding": "10.0.20348.5386",
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          },
          {
            "criteria": "cpe:2.3:o:microsoft:windows_server_2025:*:*:*:*:*:*:*:*",
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        ],
        "negate": false,
        "operator": "OR"
      }
    ]
  }
]

References

Sources include official advisories and independent security research.