Critical security updates have been rolled out to address CVE-2026-20824, a vulnerability that compromises the protection mechanism of Windows Remote Assistance. This flaw allows attackers to bypass the Mark of the Web (MOTW) defense system, which is designed to safeguard users from potentially harmful files downloaded from untrusted sources.
Disclosed on January 13, 2026, this vulnerability impacts a range of Windows platforms, including Windows 10 and Windows Server 2025. Rated with an Important severity level, CVE-2026-20824 is classified as a security feature bypass vulnerability.
The flaw enables unauthorized local attackers to circumvent MOTW defenses, which are integral in restricting risky actions on files sourced from unreliable origins. With a CVSS v3.1 score of 5.5, the vulnerability necessitates local access and user interaction for exploitation, yet it poses significant risks to confidentiality.
The root of the issue lies in a failure within Windows Remote Assistance’s protection mechanism, which is responsible for validating and processing downloaded content. Attackers cannot directly exploit this vulnerability; instead, they must employ social engineering tactics to persuade users into opening specially crafted files.
Email-based attacks are the most prevalent method, with attackers often using enticing subject lines to distribute malicious files. Alternatively, web-based attacks require users to manually download and open files from compromised or attacker-controlled websites.
Affected Systems and Patches
In response to this vulnerability, Microsoft has issued security updates for 29 distinct Windows configurations. Below is a summary of the affected systems and their corresponding patches:
| Product Family | Versions Affected | KB Articles |
|---|---|---|
| Windows 10 | Version 1607, 1809, 21H2, 22H2 | KB5073722, KB5073723, KB5073724 |
| Windows 11 | Version 23H2, 24H2, 25H2 | KB5073455, KB5074109 |
| Windows Server 2012 | 2012, 2012 R2 (all installations) | KB5073696, KB5073698 |
| Windows Server 2016 | All installations | KB5073722 |
| Windows Server 2019 | All installations | KB5073723 |
| Windows Server 2022 | All installations, 23H2 Edition | KB5073457, KB5073450 |
| Windows Server 2025 | All installations | KB5073379 |
Users of Windows 10 Version 22H2, across 32-bit, ARM64, and x64 systems, are advised to apply KB5073724. For Windows 11 deployments, including the latest versions 23H2, 24H2, and 25H2, the necessary updates are KB5073455 or KB5074109, depending on the architecture.
Organizations utilizing Windows Server 2019, 2022, and 2025 should prioritize patching using the respective knowledge base articles. Given that the vulnerability affects both client and server operating systems across multiple generations, timely patching is essential.
All updates are classified as “Required” customer actions, underscoring Microsoft’s emphasis on the necessity of these mitigations for maintaining organizational security. Currently, the vulnerability remains unexploited in the wild and was not publicly disclosed prior to the release of patches.
Microsoft’s exploitability assessment categorizes this vulnerability as “Exploitation Less Likely,” indicating that while technical barriers exist, organizations should still prioritize patching within their standard update cycles without declaring emergency-level incident response procedures.
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