Three security bypasses have been discovered in Ubuntu Linux’s unprivileged user namespace restrictions, which could be enable a local attacker to exploit vulnerabilities in kernel components.

The issues allow local unprivileged users to create user namespaces with full administrative capabilities and impact Ubuntu versions 23.10, where unprivileged user namespaces restrictions are enabled, and 24.04 which has them active by default.

Linux user namespaces allow users to act as root inside an isolated sandbox (namespace) without having the same privileges on the host.