CVE-2025-62221: Microsoft Windows Use After Free Vulnerability

What it is

Use after free in Windows Cloud Files Mini Filter Driver allows an authorized attacker to elevate privileges locally.

Exploitation evidence

First exploit evidence seen: 2025-12-09 (earliest date across the sources below).

Exploited in the wild

• CISA KEV: listed since 2025-12-09. Source

Public exploit code

GitHub proof-of-concept repositories below quality bar

1 public repositories from 1 accounts, first seen 2026-01-18.

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: CISA KEV · nomi-sec/PoC-in-GitHub.

How to fix it

CISA required action

Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable. (source: CISA KEV)

Fixed versions

• microsoft windows 10 1809: upgrade to 10.0.17763.8146 or later
• microsoft windows 10 21h2: upgrade to 10.0.19044.6691 or later
• microsoft windows 10 22h2: upgrade to 10.0.19045.6691 or later
• microsoft windows 11 23h2: upgrade to 10.0.22631.6345 or later
• microsoft windows 11 24h2: upgrade to 10.0.26100.7392 or later
• microsoft windows 11 25h2: upgrade to 10.0.26200.7392 or later
• microsoft windows server 2019: upgrade to 10.0.17763.8146 or later
• microsoft windows server 2022: upgrade to 10.0.20348.4467 or later
• microsoft windows server 2022 23h2: upgrade to 10.0.25398.2025 or later
• microsoft windows server 2025: upgrade to 10.0.26100.7392 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/en-US/vulnerability/CVE-2025-62221 (CISA KEV notes)
• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-62221 (Vendor Advisory)

MITRE ATT&CK mitigations for this chain

• M1050 Exploit Protection (for T1203) : Security applications that look for behavior used during exploitation such as Windows Defender Exploit Guard (WDEG) and the Enhanced Mitigation Experience Toolkit (EMET) can be used to mitigate some exploitation behavior. Control flow integrity checking is another way to potentially identify and stop a software exploi
• M1051 Update Software (for T1203) : Perform regular software updates to mitigate exploitation risk. Keeping software up-to-date with the latest security patches helps prevent adversaries from exploiting known vulnerabilities in client software, reducing the risk of successful attacks.
• M1048 Application Isolation and Sandboxing (for T1203) : Browser sandboxes can be used to mitigate some of the impact of exploitation, but sandbox escapes may still exist. Other types of virtualization and application microsegmentation may also mitigate the impact of client-side exploitation. Risks of additional exploits and weaknesses in those systems may still exist.

Detection Generic guidance

• Execution: Watch for the service process spawning shells or script interpreters (cmd.exe, powershell, sh, bash, python) via EDR process-tree rules.

Response checklist Generic guidance

1. Inventory: find every instance of the affected product and version (include internet-facing and forgotten ones).
2. Patch or mitigate per the vendor advisory; if you cannot patch, remove internet exposure or apply the vendor workaround.
3. Assume compromise if the system was exposed before patching: hunt for the indicators in the advisory and review logs back to the disclosure date.
4. Rotate credentials and secrets stored on or used by the affected system if compromise cannot be ruled out.