Double Free Vulnerability in Linux Kernel Affecting Xen Privileged Commands

CVE-2026-31787

What is CVE-2026-31787?

A vulnerability exists in the Linux kernel's privcmd module that can lead to a double free situation due to improper management of virtual memory areas (VMAs). When a partial unmap operation is performed on a privcmd mapping, the kernel can erroneously split the VMA without the necessary controls in place. This allows for a scenario where multiple VMAs inadvertently reference the same memory resources. Consequently, when attempting to release these resources during a closure operation, the system can execute a double freeing of the same memory, potentially leading to critical stability issues and allowing attackers to exploit this vulnerability. A safeguard fix has been implemented by introducing a .may_split callback to prevent these improper splits altogether.

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