CVE-2026-31787

描述

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

如何修補 CVE-2026-31787

要修補 CVE-2026-31787,請將受影響套件升級到下列已修補版本。

• —升級至 0 或更新版本

CVE-2026-31787 正在被利用嗎?

低 — EPSS 為 0.2%,目前沒有觀察到大規模利用活動。

受影響套件(1)

• from 0, < 0

CVSS 分數

參考連結(1)

• ADVISORYsecurity.alpinelinux.org/vuln/CVE-2026-31787