Windows Spaceport.sys contains an out‑of‑bounds write that an attacker with local privileges can exploit to inject data beyond a buffer’s bounds, resulting in arbitrary code execution. The flaw allows the attacker to gain full control of the system by escalating privileges, a classic example of the out‑of‑bounds buffer‑write weakness documented by CWE‑787.

Microsoft Windows 10 versions 1607, 1809, 21H2, 22H2; Microsoft Windows 11 versions 23H2, 24H2, 25H2, 26H1; and Microsoft Windows Server 2012, 2012 R2, 2016, 2019, 2022, 2025, including Server Core installations. All affected editions run the Spaceport.sys driver, part of the Windows networking stack.

The CVSS score of 7.8 indicates high severity, and the EPSS score of <1% shows a very low but nonzero probability of exploitation. The vulnerability is local, requiring the attacker to be present on the target machine with sufficient privilege to trigger the out‑of‑bounds write. It is not listed in CISA’s KEV catalog. The likely attack vector involves a malicious application or script that writes crafted data to the driver to achieve privilege escalation.