CVE-2026-54121: CVE-2026-54121: Improper authorization in Active Directory Certificate Services (AD CS) allows an authoriz…
microsoft · windows 10 1607 · NVD published 2026-07-14 · posted 2026-07-23 · last modified 2026-07-22
What it is
Improper authorization in Active Directory Certificate Services (AD CS) allows an authorized attacker to elevate privileges over a network.
| Weakness | CWE-285 |
|---|---|
| CVSS vector | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H (source: [email protected]) |
| ATT&CK tactics | n/a |
Exploitation evidence
First exploit evidence seen: 2026-07-23 (earliest date across the sources below).
Exploited in the wild
No source on this site lists in-the-wild exploitation yet (CISA KEV, VulnCheck KEV).
Public exploit code
GitHub proof-of-concept repositories
15 public repositories from 15 accounts, first seen 2026-07-23. Most starred: aniqfakhrul/CVE-2026-54121 (336 stars), view repository.
Verify before running: public PoCs can be malicious. Read the code and only run it in an isolated lab. A PoC means exploit code is public, not that this CVE is exploited in the wild.
Sources: nomi-sec/PoC-in-GitHub.
How to fix it
Fixed versions
- microsoft windows 10 1607: upgrade to 10.0.14393.9339 or later
- microsoft windows 10 1809: upgrade to 10.0.17763.9020 or later
- microsoft windows server 2016: upgrade to 10.0.14393.9339 or later
- microsoft windows server 2019: upgrade to 10.0.17763.9020 or later
- microsoft windows server 2022: upgrade to 10.0.20348.5386 or later
- microsoft windows server 2025: upgrade to 10.0.26100.33158 or later
Derived from the NVD CPE configuration (versionEndExcluding / versionEndIncluding). Always confirm with the vendor advisory.
Vendor advisories and patches
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-54121 (Patch, Vendor Advisory)
Detection Generic guidance
Response checklist Generic guidance
- Inventory: find every instance of the affected product and version (include internet-facing and forgotten ones).
- Patch or mitigate per the vendor advisory; if you cannot patch, remove internet exposure or apply the vendor workaround.
- Assume compromise if the system was exposed before patching: hunt for the indicators in the advisory and review logs back to the disclosure date.
- Rotate credentials and secrets stored on or used by the affected system if compromise cannot be ruled out.