Search: CVE-2025-40300

CVE-2025-40300, known as VMSCAPE, is a vulnerability in the Linux kernel affecting certain processors where insufficient branch predictor isolation exists between a guest virtual machine and a userspace hypervisor. This flaw could allow an attacker in a guest VM to potentially expose sensitive information from the host operating system. The vulnerability is mitigated by conditionally issuing an Indirect Branch Prediction Barrier (IBPB) after VMexit before returning to userspace, although this may introduce overhead for workloads frequently switching between hypervisor and userspace. The issue has been addressed in multiple Linux kernel versions with patches available. Users are advised to update their Linux kernel packages and reboot to apply the fixes. Due to ABI changes, recompilation and reinstallation of third-party kernel modules may be necessary.