CVE-2026-31787

What it is

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

At a glance

Exploitability

Can be exploited locally on the machine with a low-privilege account. High risk of data exposure, data tampering, service disruption.

Exploit odds

0.2% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2026-04-30 11:16 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-11-06 16:18 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 0.2% in the next 30 days (EPSS).
• Severity: 7.8 HIGH (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2026-04-30 11:16 UTC

Last modified

2026-11-06 16:18 UTC

Exploit probability

0.2% · EPSS, next 30 days

Weakness

CWE-415

Record status

Analyzed

Affected

• Linux Kernel < 5.10.254
• Linux Kernel < 5.15.204
• Linux Kernel < 6.1.170
• Linux Kernel < 6.6.137
• Linux Kernel < 6.12.85
• Linux Kernel < 6.18.26
• Linux Kernel < 7.0.3
• Linux Kernel 7.1

Attack profile CVSS 3.1 · 7.8

Attack vector

Local

Complexity

Low

Privileges needed

Low

User interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2026-31787.md and follow it. Check whether this project is affected by CVE-2026-31787. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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