A heap‑based buffer overflow in the Windows Client‑Side Caching (CSC) Service permits an unauthorized attacker to elevate privileges. The flaw allows maliciously crafted network traffic to be processed by the CSC service, causing it to write beyond the bounds of a heap buffer. An attacker exploiting this can gain higher privileges on the targeted Windows system, potentially enabling full control of the machine. The weakness corresponds to CWE‑122 (Heap Based Buffer Overflow) and CWE‑822 (Improper Validation of Input From System Function).

The vulnerability affects numerous Microsoft Windows editions, including Windows 10 from version 1607 through 22H2, Windows 11 from version 23H2 through 26H2, and multiple Windows Server releases ranging from Server 2012 to Server 2025. All architectures listed, such as x86, x64, and ARM64, are included in the affected inventory.

The CVSS score of 8.8 classifies this issue as high severity. The EPSS score is not available, so the current exploitation probability in the wild is unknown, but the vulnerability is not listed in the CISA Known Exploited Vulnerabilities catalog. Based on the description, the likely attack vector is network‑based, requiring an attacker to send a specially crafted packet to the CSC service. Once the overflow is triggered, elevation of privileges can occur without additional credentials, making the flaw a serious threat to the confidentiality, integrity, and availability of affected systems.