An out‑of‑bounds write flaw in the Microsoft RPC Runtime library allows an attacker to craft malicious RPC requests that overwrite memory and execute arbitrary code. The vulnerability is exploitable over the network with no privileged credentials required, meaning an attacker who can reach the vulnerable endpoint can gain full control of the affected system.

Microsoft Windows 10 versions 1607, 1809, 21H2, 22H2; Windows 11 versions 23H2, 24H2, 25H2, 26H1; Windows Server 2012, Server 2012 R2, Server 2016, Server 2019, Server 2022, Server 2025, including all Server Core installations.

The CVSS score of 9.8 indicates a high‑severity remote code execution risk. EPSS information is not available, and the vulnerability is not listed in the CISA KEV catalog, but the lack of a KEV listing does not diminish the likelihood that adversaries will attempt exploitation. Attackers likely target exposed RPC services over the network, leveraging the out‑of‑bounds write to execute arbitrary payloads. The vulnerability is exploitable only when an RPC endpoint is reachable from the attacker’s network, but once reached, no further authentication or privilege escalation is required.