CVE-2026-21247 is a high-severity vulnerability identified in Microsoft Windows Hyper-V, published on February 10, 2026. This vulnerability allows an authorized attacker to execute code locally through improper input validation. The CVSS score for this vulnerability is 7.3, indicating a high level of risk to organizations that utilize affected Windows versions. The risk associated with this vulnerability is significant, as it can lead to unauthorized code execution, potentially compromising sensitive information and system integrity.
Given the nature of this vulnerability, organizations should prioritize patching immediately. The potential impacts include high confidentiality, integrity, and availability risks, which could severely disrupt operations and data security.
Currently, there are no public exploits or known proof-of-concept codes available for CVE-2026-21247, but the exploitability score of 1.3 indicates a concerning level of risk. Organizations are urged to remain vigilant and address this vulnerability promptly.
The urgency for defenders is heightened due to the local attack vector and low attack complexity, which could make exploitation feasible for various attackers. Organizations must ensure they have a robust patch management process in place to mitigate risks associated with vulnerabilities like this.
Vulnerability Details
The vulnerability is classified as improper input validation, with associated CWE IDs including CWE-20, CWE-122, and CWE-125. This classification highlights the weaknesses in the input handling mechanism of Windows Hyper-V, allowing local attackers to manipulate inputs and execute arbitrary code.
The CVSS score of 7.3 categorizes this vulnerability as high severity, emphasizing the need for immediate attention. The affected products include various versions of Windows 10 and Windows 11, as well as multiple Windows Server editions, underscoring the widespread impact of this issue.
Technical Analysis
The root cause of this vulnerability lies in improper input validation within Windows Hyper-V. Attackers may leverage this vulnerability by executing code with local privileges, requiring low complexity and user interaction. This means that an attacker must have some level of access to the system, thereby increasing the risk for organizations that may not have properly restricted local user access.
The impacts of this vulnerability include high confidentiality, integrity, and availability risks. If exploited, attackers could gain unauthorized access to sensitive data, alter system behaviors, and potentially render systems unavailable.
Risk & Impact Analysis
Risk to organizations includes unauthorized code execution, which could lead to significant data breaches or system disruptions. The blast radius of this vulnerability is considerable, affecting multiple Windows versions widely used in enterprise environments. Given the current threat landscape, it is essential for organizations to assess their exposure and take appropriate action.
The urgency for remediation is classified as high due to the CVSS score and the potential for exploitation. Organizations should prioritize this vulnerability in their patch management cycles and ensure that they have the necessary controls in place to mitigate the risk.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
The affected versions include Windows 10 (1607, 1809, 21H2, 22H2), Windows 11 (23H2, 24H2, 25H2), and various Windows Server versions (2016, 2019, 2022, 2025). Organizations should note that all versions prior to vendor patch are vulnerable.
Mitigation & Remediation
Organizations should prioritize patching to the latest versions of affected Windows operating systems. For those unable to apply patches immediately, implementing strict access controls and monitoring local user activities can help reduce the risk of exploitation. Additionally, organizations should consider engaging in penetration testing to identify any potential vulnerabilities in their systems.
Detection Guidance
Organizations should monitor logs for indicators of unauthorized access attempts, unexpected code execution, and other behavioral anomalies. Implementing network signatures to detect unusual patterns of behavior can also aid in early detection of exploitation attempts.
AppSecure Threat Intelligence Insight
The long-term significance of CVE-2026-21247 lies in its demonstration of the ongoing need for rigorous input validation in software development. This vulnerability highlights that even authorized users pose risks if input validation mechanisms are inadequate. Security teams should take this as a lesson to reinforce their development practices with a focus on secure coding principles.
As part of a comprehensive security strategy, organizations should regularly assess their vulnerabilities and ensure that all software components are updated. For more insights on vulnerability management, organizations can consult our guide on vulnerability management programs and consider adopting penetration testing methodologies to further enhance their security posture.
Finally, organizations should not overlook the importance of continuous security assessments, as they play a crucial role in identifying and mitigating emerging threats effectively.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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