CVE-2026-62815

Microsoft QUIC is a networking component Windows uses to move data efficiently. This vulnerability is like a “broken memory reference” where Windows can end up using a freed chunk of memory; if an attacker can reach it over the network, they may be able to run their own code on your machine.

This matters if you run Windows 11, Windows Server 2022, or Windows Server 2025 on machines that are reachable over the network where QUIC traffic could be processed. Because it’s remote and doesn’t require a login, the risk is highest for systems that accept inbound network connections from clients or the public internet. Treat it as a risk when the vulnerable component is reachable from an attacker over the network (for example, if your server is publicly reachable or broadly network-accessible).

This is RED because the vulnerability is being actively targeted, with press reporting exploitation activity (including attribution to the Lazarus group). It allows attackers to execute code remotely over the network, meaning a fully patched device is the primary way to stop compromise. Prioritize updating affected Windows systems as soon as possible.