This vulnerability (CVE-2026-42915) involves an incorrect calculation of buffer size within the Windows VMSwitch component on Windows 10 Version 21H2 (build 10.0.19044.0). An authorized attacker with local access can exploit this flaw to cause a denial of service (DoS) by triggering conditions that lead to resource exhaustion or system instability. The vulnerability has a CVSS 3.1 base score of 5.5, reflecting a medium severity level. Microsoft has released an official fix to remediate this issue.

The vulnerability allows an authorized local attacker to cause a denial of service on affected Windows 10 Version 21H2 systems by exploiting incorrect buffer size calculations in the VMSwitch component. There is no impact on confidentiality or integrity, only availability is affected. No known exploits are reported in the wild at this time.

An official fix is available from Microsoft to address this vulnerability. Users and administrators should apply the security update provided by Microsoft as detailed in the vendor advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-42915 to remediate this issue.