Active attack: Dirty Frag Linux vulnerability expands post-compromise risk

This collection of Microsoft Security Blog posts highlights multiple active and high-impact threats and security developments. A newly disclosed Linux local privilege-escalation vulnerability dubbed “Dirty Frag” (affecting kernel networking/memory-fragment handling components such as esp4, esp6, and rxrpc) enables reliable escalation from unprivileged user to root and is being monitored with detection coverage in Microsoft Defender. Separately, CVE-2026-31431 (“Copy Fail”) is a high-severity Linux root escalation affecting cloud and Kubernetes workloads with a working exploit in the wild. New/