CVE-2026-56155
HighExploitedPublic exploitInsufficient granularity of access control in Active Directory Federation Services (AD FS) allows an authorized attacker to elevate privileges locally.
Published Jul 14, 2026 · Updated Oct 8, 2026
Key Facts
Patch immediately- CVE-2026-56155 is a high-severity vulnerability (CVSS 7.8 v3.1) affecting Windows 10 1607 (Microsoft), Windows 10 1809 (Microsoft), Windows Server 2012 (Microsoft) and 12 more products.
- It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since Jul 14, 2026. Public exploit code is available.
- EPSS estimates a 0.3% probability of exploitation in the next 30 days.
- Fixed versions are available, including Windows 10 1607 10.0.14393.9339, Windows 10 1809 10.0.17763.9020, Windows Server 2012 6.2.9200.26226.
- Brandefense priority: patch immediately, because it is listed as exploited in the wild.
CVSS v3.1
7.8
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
EPSS (30-day exploit likelihood)
0.3%
Higher than 26.6% of all scored CVEs
Exploited in the wild
Yes
4 catalog listings
Public exploit code
Available
Proof-of-concept or weaponized module
Get the full CVE-2026-56155 brief as a PDF
Every affected product and fixed release, exploitation status and a first 24 hours response checklist, emailed within minutes.
Description
Insufficient granularity of access control in Active Directory Federation Services (AD FS) allows an authorized attacker to elevate privileges locally.
Known-Exploited Catalog Listings
| Catalog | Added | Remediation due | Ransomware use |
|---|---|---|---|
| CISA KEV | Jul 14, 2026 | Jul 28, 2026 | Not reported |
| Industry KEV feed | Jul 14, 2026 | Jul 28, 2026 | Not reported |
| CIRCL KEV | Jul 14, 2026 | Jul 28, 2026 | Not reported |
| ENISA EUVD | Jul 14, 2026 | n/a | Not reported |
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.
Affected Products
36 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| Windows 10 1607Microsoft | 10.0.14393.9339 | 10.0.14393.9339 |
| Windows 10 1809Microsoft | 10.0.17763.9020 | 10.0.17763.9020 |
| Windows Server 2012Microsoft | 6.2.9200.26226, r2, >= 6.2.9200.0 | 6.2.9200.26226 |
| windows server 2012 R2Microsoft | 6.3.9600.23291, >= 6.3.9600.0 | 6.3.9600.23291 |
| Windows Server 2016Microsoft | 10.0.14393.9339, >= 10.0.14393.0 | 10.0.14393.9339 |
Patched Releases
Windows 10 1607
10.0.14393.9339
Windows 10 1809
10.0.17763.9020
Windows Server 2012
6.2.9200.26226
windows server 2012 R2
6.3.9600.23291
Windows Server 2016
10.0.14393.9339
Windows Server 2019
10.0.17763.9020
Windows Server 2022
10.0.20348.5386
Windows Server 2025
10.0.26100.33158
Windows 10 Version 1607
10.0.14393.9339
Windows 10 Version 1809
10.0.17763.9020
Windows Server 2012 (Server Core installation)
6.2.9200.26226
Windows Server 2012 R2 (Server Core installation)
6.3.9600.23291
Windows Server 2016 (Server Core installation)
10.0.14393.9339
Windows Server 2019 (Server Core installation)
10.0.17763.9020
Windows Server 2025 (Server Core installation)
10.0.26100.33158
Timeline
Publicly disclosed
Jul 14, 2026
Added to CISA KEV
Jul 14, 2026
Added to Industry KEV feed
Jul 14, 2026
Added to CIRCL KEV
Jul 14, 2026
Added to ENISA EUVD
Jul 14, 2026
Last updated
Oct 8, 2026
Weakness Type
- CWE-1220 Insufficient Granularity of Access Control
References
- advisoryJVN JVNDB-2026-032925
- exploitVulnCheck exploitation report
- exploitVulnCheck exploitation report
- exploitVulnCheck exploitation report
- exploitVulnCheck exploitation report
FAQ
Common Questions.
Insufficient granularity of access control in Active Directory Federation Services (AD FS) allows an authorized attacker to elevate privileges locally.
Affected: Windows 10 1607 (Microsoft) versions 10.0.14393.9339; Windows 10 1809 (Microsoft) versions 10.0.17763.9020; Windows Server 2012 (Microsoft) versions 6.2.9200.26226, r2, >= 6.2.9200.0, among others. The full list is in the CVE brief.
It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since Jul 14, 2026.
Yes. It was added on Jul 14, 2026 with a federal remediation due date of Jul 28, 2026.
Public exploit code is available.
Fixed versions are available, including Windows 10 1607 10.0.14393.9339, Windows 10 1809 10.0.17763.9020, Windows Server 2012 6.2.9200.26226.
Brandefense priority: patch immediately, because it is listed as exploited in the wild.
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