CVE-2026-31787

High

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

Package Linux Kernel
Published 2026-04-30
Last modified 2026-05-06
CVSS version 3.1
Patch available
Yes

CVSS 3.1 score

7.8

out of 10
High
Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High
Vector string
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Weakness type

CWE-415

CVE-2026-31787 is classified as CWE-415

See CWE-415 on MITRE CWE for full details on this weakness type.

Affected versions

Linux kernel versions 3.8 and later are affected. Fixed in 5.10.254, 5.15.204, 6.1.170, 6.6.137, 6.12.85, 6.18.26, 7.0.3, 7.1-rc2 and their respective stable series.

Affected from
≥ 3.8
Fixed in
✓ 5.10.254 5.10.x ✓ 5.15.204 5.15.x ✓ 6.1.170 6.1.x ✓ 6.6.137 6.6.x ✓ 6.12.85 6.12.x ✓ 6.18.26 6.18.x ✓ 7.0.3 7.0.x ✓ 7.1-rc2

References

The following references provide additional information about CVE-2026-31787 including vendor advisories, patch commits, exploit details, and third-party analysis. Links are sourced from the NIST NVD database.

8 patch commits total View all on NVD

Frequently asked questions

  • What is CVE-2026-31787?

    CVE-2026-31787 is a High severity Linux kernel vulnerability with a CVSS score of 7.8 out of 10 . It affects Linux kernel versions from 3.8 onward and has been patched in 5.10.254, 5.15.204, 6.1.170 and others. CVE-2026-31787 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

  • What is the CVSS score for CVE-2026-31787?

    CVE-2026-31787 has a CVSS score of 7.8 out of 10, rated High severity (CVSS 3.1). The vector string is CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H .

  • Is there a patch available for CVE-2026-31787?

    Yes — CVE-2026-31787 has been patched. Fixed versions include 5.10.254, 5.15.204, 6.1.170 and others. If you are running Linux kernel 3.8 or later up to the fix versions, apply the relevant patch for your kernel branch.

  • Is CVE-2026-31787 actively exploited?

    No — CVE-2026-31787 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.

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