CVE-2026-31787: Linux Kernel

High severity, CVSS 7.8. EPSS: 0.2% chance of exploitation in the next 30 days.

In the Linux kernel, the following vulnerability has been resolved: xen/privcmd: fix double free via VMA splitting privcmd_vm_ops defines .close (privcmd_close), but neither .may_split nor .open. When userspace does a partial munmap() on a privcmd mapping, the kernel splits the VMA via __split_vma(). Since may_split is NULL, the split is allowed. vm_area_dup() copies vm_private_data (a pages array allocated in alloc_empty_pages()) into the new VMA without any fixup, because there is no .open callback. Both VMAs now point to the same pages array. When the unmapped portion is closed, privcmd_close() calls: - xen_unmap_domain_gfn_range() - xen_free_unpopulated_pages() - kvfree(pages) The surviving VMA still holds the dangling pointer. When it is later destroyed, the same sequence runs again, which leads to a double free. Fix this issue by adding a .may_split callback denying the VMA split. This is XSA-487 / CVE-2026-31787

Affected products

• Linux Linux Kernel: from 3.8, before 5.10.254 (fixed in 5.10.254); from 5.11, before 5.15.204 (fixed in 5.15.204); from 5.16, before 6.1.170 (fixed in 6.1.170); from 6.2, before 6.6.137 (fixed in 6.6.137); from 6.7, before 6.12.85 (fixed in 6.12.85); from 6.13, before 6.18.26 (fixed in 6.18.26); …

Published 2026-04-30. Last modified 2026-06-17.