DirtyClone Linux Kernel LPE Flaw Lets Local Users Gain Root Access

DirtyClone (CVE-2026-43503) is a high-severity Linux kernel local privilege escalation in the DirtyFrag family that allows an unprivileged local user to gain root by exploiting a missing SKBFL_SHARED_FRAG flag propagation during packet cloning (via __pskb_copy_fclone()/netfilter TEE), enabling writes into file-backed page-cache memory without on-disk changes; affected distributions include Debian, Ubuntu, and Fedora where unprivileged user namespaces are enabled, and mitigations include upgrading to kernel v7.1-rc5 or applying backported patches, disabling unprivileged user namespaces, or blacklisting IPsec modules.