Fragnesia Universal Linux Root LPE Details and One-Line PoC Disclosed

Fragnesia is a disclosed Linux kernel local privilege escalation (LPE) that abuses a logic flaw in the networking subsystem to modify VFS page-cache contents—allowing an unprivileged user to obtain a persistent root shell in memory without altering on-disk binaries. The researchers published full technical details and a simple PoC (one-line build/run command), affected all kernels released before May 13, 2026, and recommend immediate patching or unloading of esp4/esp6/rxrpc modules as temporary mitigation.