CVE-2026-56155: Microsoft Active Directory Federation Services Insufficient Granularity of Access Control Vulnerability
Advisory generated from the CVE record, CISA, Exploit Observer and VEDAS: what it is, whether it is exploited, who is affected, and how to fix and detect it.
Generated by VEDAS. Scores as of 2026-11-01 19:19 UTC. Rebuilt every few hours from cve-scores, CISA KEV and vedas-signatures. How this works and its limits.
What it is
Insufficient granularity of access control in Active Directory Federation Services (AD FS) allows an authorized attacker to elevate privileges locally.
Description quoted from the CVE record (assigned by microsoft, published 2026-07-14).
Weakness: CWE-1220: Insufficient Granularity of Access Control
How it can be exploited
Exploitable with local access with low attack complexity needing low privileges and no user interaction. Impact: confidentiality high, integrity high, availability high. CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:F/RL:O/RC:C
CISA assessment (SSVC): CISA assesses exploitation as active. Automatable: no. Technical impact: total.
- On CISA KEV since
- 2026-07-14
- US federal deadline
- 2026-07-28
- Ransomware use
- Not known
Public exploit evidence (Exploit Observer)
Also known as: BDU:2026-09722, EUVD-2026-44042, GHSA-p436-qch3-9m59
Exploit Observer has no public exploit code that names this CVE or one of its aliases.
Vulnerability databases and vendor advisories (5)
Catalogue entries, not exploit evidence.
- Vulnerability database or vendor advisory: https://euvd.enisa.europa.eu/enisa/EUVD-2026-44042
- Vulnerability database or vendor advisory: https://github.com/advisories/GHSA-p436-qch3-9m59
- Vulnerability database or vendor advisory: https://msrc.microsoft.com/update-guide/en-US/vulnerability/CVE-2026-56155
- Vulnerability database or vendor advisory: https://nvd.nist.gov/vuln/detail/CVE-2026-56155
- Vulnerability database or vendor advisory: https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-56155
2 more references returned by Exploit Observer did not name this CVE or an alias, so they are left out.
VEDAS data as of 2026-11-01T17:12 UTC; fetched 2026-11-02.
Live scores
- EPSS
- 0.003
low predicted chance of attack - VEDAS
- 0.515
some exploit evidence - On CISA KEV
- Yes, since 2026-07-14
- Detection rule
- Out of scope (local)
Thin horizontal line: the “likely” (EPSS 0.10) or “strong” (VEDAS 0.90) threshold. Shaded “no data” areas are periods when cve-scores did not publish.
Who is affected
| Product | Affected | Not affected |
|---|---|---|
| Microsoft Windows 10 Version 1607 | from 10.0.14393.0 before 10.0.14393.9339 | Not stated |
| Microsoft Windows 10 Version 1809 | from 10.0.17763.0 before 10.0.17763.9020 | Not stated |
| Microsoft Windows Server 2012 | from 6.2.9200.0 before 6.2.9200.26226 | Not stated |
| Microsoft Windows Server 2012 (Server Core installation) | from 6.2.9200.0 before 6.2.9200.26226 | Not stated |
| Microsoft Windows Server 2012 R2 | from 6.3.9600.0 before 6.3.9600.23291 | Not stated |
| Microsoft Windows Server 2012 R2 (Server Core installation) | from 6.3.9600.0 before 6.3.9600.23291 | Not stated |
| Microsoft Windows Server 2016 | from 10.0.14393.0 before 10.0.14393.9339 | Not stated |
| Microsoft Windows Server 2016 (Server Core installation) | from 10.0.14393.0 before 10.0.14393.9339 | Not stated |
| Microsoft Windows Server 2019 | from 10.0.17763.0 before 10.0.17763.9020 | Not stated |
| Microsoft Windows Server 2019 (Server Core installation) | from 10.0.17763.0 before 10.0.17763.9020 | Not stated |
| Microsoft Windows Server 2022 | from 10.0.20348.0 before 10.0.20348.5386 | Not stated |
| Microsoft Windows Server 2025 | from 10.0.26100.0 before 10.0.26100.33158 | Not stated |
| Microsoft Windows Server 2025 (Server Core installation) | from 10.0.26100.0 before 10.0.26100.33158 | Not stated |
Version ranges exactly as the CVE record states them. “Before X” means X is the first fixed version.
Exploit Observer also maps it to: microsoft windows_10_1607, microsoft windows_10_1809, microsoft windows_server_2012, microsoft windows_server_2016, microsoft windows_server_2019, microsoft windows_server_2022, microsoft windows_server_2025, microsoft_corp windows_server_2012, microsoft_corp windows_server_2012_(server_core_installation), microsoft_corp windows_server_2012_r2.
How to fix it
Fixed versions stated in the CVE record: 10.0.14393.9339, 10.0.17763.9020, 6.2.9200.26226, 6.3.9600.23291, 10.0.20348.5386, 10.0.26100.33158.
CISA 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.
Vendor guidance:
- Active Directory Federation Services Elevation of Privilege Vulnerability (vendor-advisory, patch)
How to detect it
This bug needs local access to exploit. VEDAS signatures cover remotely exploitable bugs for now, so there is no network rule or remote check for it. Patch it and watch your endpoint telemetry for unusual local activity.
References
Vendor advisories and patches
- Active Directory Federation Services Elevation of Privilege Vulnerability (vendor-advisory, patch)
Government sources
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-56155 (government-resource)
Other databases
Where this comes from
This advisory is generated automatically by VEDAS from: CVE.org record, CISA KEV, cve-scores (EPSS and VEDAS), Exploit Observer. Text in quotes is reproduced from the source; everything else is a fixed template filled with source fields. Nothing here is written by a language model. Check the vendor advisory before acting, and read how VEDAS and Exploit Observer work, and their limits.