# CVE-2026-54121 — Microsoft Windows 10 Version 1607

> As of 2026-07-26, CVE-2026-54121 is a HIGH-severity vulnerability in Microsoft Windows 10 Version 1607, CVSS v3.1 8.8, EPSS 1.0% (60.8th percentile). Threadlinqs Intelligence links 1 tracked threat campaign to CVE-2026-54121, most recently “CVE-2026-54121 ("Certighost"): Low-Privileged AD CS Enrollment Flaw Enables Domain Controller Impersonation”.

**Last updated:** 2026-07-26

## What is CVE-2026-54121?

Improper authorization in Active Directory Certificate Services (AD CS) allows an authorized attacker to elevate privileges over a network.

The record classifies CVE-2026-54121 under weakness class [CWE-285](https://intel.threadlinqs.com/cwe/CWE-285). Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs low-privilege credentials, needs no user interaction, and has high impact on confidentiality, integrity, availability. 12 affected-product entries are recorded, across 1 vendor, listed below. The identifier was first published 83 days ago.

## Severity and exploitation probability

- **CVSS v3.1 base score:** 8.8 — HIGH (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C`)
- **EPSS (FIRST):** 1.0% probability of exploitation in the next 30 days, higher than 60.8% of all scored CVEs
- **CISA KEV:** Not listed in the CISA Known Exploited Vulnerabilities catalog
- **Threadlinqs priority:** 8.8/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- **Published:** 2026-07-14, last modified 2026-07-26

## Is CVE-2026-54121 being exploited?

Weaponised exploit code for CVE-2026-54121 is publicly available. 5 public proof-of-concept repositories are tracked for this identifier.

- [aniqfakhrul/CVE-2026-54121](https://github.com/aniqfakhrul/CVE-2026-54121) (github)
- [tc4dy/CVE-2026-54121-PoC-Exploit](https://github.com/tc4dy/CVE-2026-54121-PoC-Exploit) (github)
- [0xBlackash/CVE-2026-54121](https://github.com/0xBlackash/CVE-2026-54121) (github)
- [HORKimhab/CVE-2026-54121](https://github.com/HORKimhab/CVE-2026-54121) (github)
- [GlendonNotGlen/certighost-cve-2026-54121-slides](https://github.com/GlendonNotGlen/certighost-cve-2026-54121-slides) (github)

## Affected products and versions

- [Microsoft](https://intel.threadlinqs.com/vendors/microsoft): Windows 10 Version 1607, Windows 10 Version 1809, Windows Server 2012, Windows Server 2012 (Server Core installation), Windows Server 2012 R2, Windows Server 2012 R2 (Server Core installation), Windows Server 2016, Windows Server 2016 (Server Core installation), Windows Server 2019, Windows Server 2019 (Server Core installation), Windows Server 2022, Windows Server 2025

## How to fix CVE-2026-54121

The record marks a vendor fix as available for CVE-2026-54121. Patch reference: [https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-54121](https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-54121). Vendor advisory: [https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-54121](https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-54121). Apply the vendor fix referenced above to every affected product listed in this record, then confirm the running version against the vendor advisory.

## Threat activity tracking CVE-2026-54121

1 tracked threat in the Threadlinqs corpus references CVE-2026-54121, either in the campaign’s CVE list or as an indicator on the campaign record.

- [CVE-2026-54121 ("Certighost"): Low-Privileged AD CS Enrollment Flaw Enables Domain Controller Impersonation](https://intel.threadlinqs.com/threat/TL-2026-1675) — CRITICAL · 2026-07-24

## Sources

Enriched from CVE.org, NVD, FIRST EPSS, GitHub Security Advisories, public proof-of-concept repositories. Last verified by Threadlinqs on 2026-07-26. This product uses the NVD API but is not endorsed or certified by the NVD.

**Vendor advisory and patch**

- [msrc.microsoft.com — vendor advisory](https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-54121)

Canonical: https://intel.threadlinqs.com/cve/CVE-2026-54121
Full detection coverage and IOCs for threats exploiting CVE-2026-54121 via the Threadlinqs MCP server (Purple tier): https://intel.threadlinqs.com/mcp