Three Bypasses of Ubuntu's Unprivileged User Namespace Restrictions

Qualys Security Advisory details three bypasses discovered in Ubuntu 24.04's unprivileged user namespace restrictions. Attackers can leverage default tools like aa-exec and busybox, or use LD_PRELOAD to gain administrator privileges within a namespace, circumventing security measures. These exploits take advantage of AppArmor profiles that allow creating namespaces with full capabilities, potentially enabling exploitation of kernel vulnerabilities requiring privileges like CAP_SYS_ADMIN or CAP_NET_ADMIN.