CVE-2026-69819

CVE-2026-69819 is an out-of-bounds write (memory corruption) in Microsoft's Windows RPC Runtime, the core library that handles remote procedure call traffic on virtually every Windows system. An unauthenticated remote attacker can trigger it by sending a specially crafted RPC request over the network to a reachable RPC endpoint, with no privileges and no user interaction required (CVSS 9.8, AV:N/AC:L/PR:N/UI:N). Successful exploitation gives the attacker code execution on the target host with full impact to confidentiality, integrity, and availability. Because the RPC Runtime ships with all Windows installations, any Windows desktop or server with an RPC endpoint reachable by an attacker is potentially exposed. As of now there is no known exploitation in the wild, no public proof of concept, and the issue is not on the CISA KEV list, though the severity makes it a credible candidate for future weaponization.

What to do: Apply Microsoft's security update for CVE-2026-69819 to all Windows desktops and servers via Windows Update/WSUS as soon as it is released, prioritizing internet-facing systems. Ensure perimeter firewalls block TCP/135 and the dynamic RPC port range (49152–65535), and scan your address space to confirm no host exposes RPC to the internet. Monitor RPCSS crash events and network telemetry for malformed RPC traffic, and review Microsoft's advisory for any detection and workaround guidance.