Fragnesia Extends Linux Kernel Security Challenge with Root-Level Exploit

A newly disclosed Linux kernel privilege-escalation vulnerability (CVE-2026-46300, "Fragnesia") in the XFRM ESP-in-TCP subsystem allows unprivileged users to corrupt file-backed page cache entries in memory and obtain root access without modifying disk files. The flaw—reported as predictable and avoiding race conditions—affects multiple major distributions; vendors have issued advisories and recommended temporary mitigations (disabling esp4/esp6/rxrpc, restricting unprivileged namespaces). Public exploit demonstrations exist, but researchers have not observed confirmed in-the-wild exploitation to date.