# CVE-2026-56155: Microsoft Active Directory Federation Services Insufficient Granularity of Access Control Vulnerability

> An authorized attacker can elevate privileges locally due to insufficient access control granularity in Active Directory Federation Services.

- **Severity:** High 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`)
- **Exploited in the wild:** Yes, since 14 Jul 2026 (CISA KEV)
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 14 Jul 2026
- **Updated:** 28 Oct 2026
- **Also known as:** GHSA-p436-qch3-9m59

## What is CVE-2026-56155?

CVE-2026-56155 is a high-severity vulnerability in Microsoft Windows 10 1607, published on 14 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

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

Weakness: CWE-1220 (Insufficient Granularity of Access Control)

## Which versions are affected by CVE-2026-56155?

It affects 7 products.


Products: 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.

## How do I fix CVE-2026-56155?

No fix has been published for CVE-2026-56155 yet. Limit exposure of the affected software until one is available. US federal agencies must fix it by 28 Jul 2026.

## Is CVE-2026-56155 being exploited?

Yes. Attackers have exploited CVE-2026-56155 in the wild since at least 14 Jul 2026.

## Other vulnerabilities in Microsoft Windows 10 1607

- [CVE-2026-33824](https://insights.sbomify.com/CVE-2026-33824/): Microsoft Internet Key Exchange (IKE) Service Extensions Double Free (critical 9.8, exploited in the wild)
- [CVE-2026-21510](https://insights.sbomify.com/CVE-2026-21510/): Microsoft Windows Shell Protection Mechanism Failure (high 8.8, exploited in the wild)
- [CVE-2026-21513](https://insights.sbomify.com/CVE-2026-21513/): Microsoft MSHTML Framework Protection Mechanism Failure (high 8.8, exploited in the wild)
- [CVE-2023-32049](https://insights.sbomify.com/CVE-2023-32049/): Microsoft Windows Defender SmartScreen Security Feature Bypass (high 8.8, exploited in the wild)
- [CVE-2023-29360](https://insights.sbomify.com/CVE-2023-29360/): Microsoft Streaming Service Untrusted Pointer Dereference (high 8.4, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-56155 and fix it if it is affected.

What it is: CVE-2026-56155 is a high-severity vulnerability in Microsoft Windows 10 1607, published on 14 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: Yes. Attackers have exploited CVE-2026-56155 in the wild since at least 14 Jul 2026.

Affected product: Microsoft Windows 10 1607. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-56155/ (Markdown: https://insights.sbomify.com/CVE-2026-56155/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-56155
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-56155
- OSV: https://osv.dev/vulnerability/CVE-2026-56155

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-56155/
Summaries are generated and may contain mistakes; the official description above is the record.