CVE-2026-31787 (GCVE-0-2026-31787)

Vulnerability from cvelistv5 – Published: 2026-04-30 10:31 – Updated: 2026-06-14 17:44
VLAI
Title
xen/privcmd: fix double free via VMA splitting
Summary
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
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: d71f513985c22f1050295d1a7e4327cf9fb060da , < dbf862ce9f009128ab86b234d91413a3e450beb4 (git)
Affected: d71f513985c22f1050295d1a7e4327cf9fb060da , < 2b985d3a024b9e8c24e21671b34e855569763808 (git)
Affected: d71f513985c22f1050295d1a7e4327cf9fb060da , < 1576ff3869cbd3620717195f971c85b7d7fd62b5 (git)
Affected: d71f513985c22f1050295d1a7e4327cf9fb060da , < 402d84ad9e89bd4cbfd07ca8598532b7021daf95 (git)
Affected: d71f513985c22f1050295d1a7e4327cf9fb060da , < 2894a351fe2ea8684919d36df3188b9a35e3926f (git)
Affected: d71f513985c22f1050295d1a7e4327cf9fb060da , < 446ee446d9ae66f36e95c3c90bbcc4e56b94cde0 (git)
Affected: d71f513985c22f1050295d1a7e4327cf9fb060da , < 71bf829800758a6e3889096e4754ef47ba7fc850 (git)
Affected: d71f513985c22f1050295d1a7e4327cf9fb060da , < 24daca4fc07f3ff8cd0e3f629cd982187f48436a (git)
Create a notification for this product.
Linux Linux Affected: 3.8
Unaffected: 0 , < 3.8 (semver)
Unaffected: 5.10.254 , ≤ 5.10.* (semver)
Unaffected: 5.15.204 , ≤ 5.15.* (semver)
Unaffected: 6.1.170 , ≤ 6.1.* (semver)
Unaffected: 6.6.137 , ≤ 6.6.* (semver)
Unaffected: 6.12.85 , ≤ 6.12.* (semver)
Unaffected: 6.18.26 , ≤ 6.18.* (semver)
Unaffected: 7.0.3 , ≤ 7.0.* (semver)
Unaffected: 7.1 , ≤ * (original_commit_for_fix)
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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
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  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


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