xen/privcmd: fix double free via VMA splitting
Summary
| CVE | CVE-2026-31787 |
|---|---|
| State | PUBLISHED |
| Assigner | Linux |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-04-30 11:16:21 UTC |
| Updated | 2026-05-04 09:16:00 UTC |
| Description | 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 |
Risk And Classification
EPSS: 0.000330000 probability, percentile 0.094820000 (date 2026-05-03)
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Linux | Linux | affected d71f513985c22f1050295d1a7e4327cf9fb060da dbf862ce9f009128ab86b234d91413a3e450beb4 git | Not specified |
| CNA | Linux | Linux | affected d71f513985c22f1050295d1a7e4327cf9fb060da 2b985d3a024b9e8c24e21671b34e855569763808 git | Not specified |
| CNA | Linux | Linux | affected d71f513985c22f1050295d1a7e4327cf9fb060da 1576ff3869cbd3620717195f971c85b7d7fd62b5 git | Not specified |
| CNA | Linux | Linux | affected d71f513985c22f1050295d1a7e4327cf9fb060da 402d84ad9e89bd4cbfd07ca8598532b7021daf95 git | Not specified |
| CNA | Linux | Linux | affected d71f513985c22f1050295d1a7e4327cf9fb060da 2894a351fe2ea8684919d36df3188b9a35e3926f git | Not specified |
| CNA | Linux | Linux | affected d71f513985c22f1050295d1a7e4327cf9fb060da 446ee446d9ae66f36e95c3c90bbcc4e56b94cde0 git | Not specified |
| CNA | Linux | Linux | affected d71f513985c22f1050295d1a7e4327cf9fb060da 71bf829800758a6e3889096e4754ef47ba7fc850 git | Not specified |
| CNA | Linux | Linux | affected d71f513985c22f1050295d1a7e4327cf9fb060da 24daca4fc07f3ff8cd0e3f629cd982187f48436a git | Not specified |
| CNA | Linux | Linux | affected 3.8 | Not specified |
| CNA | Linux | Linux | unaffected 3.8 semver | Not specified |
| CNA | Linux | Linux | unaffected 5.10.254 5.10.* semver | Not specified |
| CNA | Linux | Linux | unaffected 5.15.204 5.15.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.1.170 6.1.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.6.137 6.6.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.12.85 6.12.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.18.26 6.18.* semver | Not specified |
| CNA | Linux | Linux | unaffected 7.0.3 7.0.* semver | Not specified |
| CNA | Linux | Linux | unaffected 7.1-rc2 * original_commit_for_fix | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| git.kernel.org/stable/c/2b985d3a024b9e8c24e21671b34e855569763808 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| www.openwall.com/lists/oss-security/2026/04/28/14 | af854a3a-2127-422b-91ae-364da2661108 | www.openwall.com | |
| git.kernel.org/stable/c/24daca4fc07f3ff8cd0e3f629cd982187f48436a | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/402d84ad9e89bd4cbfd07ca8598532b7021daf95 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| xenbits.xen.org/xsa/advisory-487.html | af854a3a-2127-422b-91ae-364da2661108 | xenbits.xen.org | |
| git.kernel.org/stable/c/1576ff3869cbd3620717195f971c85b7d7fd62b5 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/446ee446d9ae66f36e95c3c90bbcc4e56b94cde0 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/dbf862ce9f009128ab86b234d91413a3e450beb4 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/2894a351fe2ea8684919d36df3188b9a35e3926f | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/71bf829800758a6e3889096e4754ef47ba7fc850 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
No vendor comments have been submitted for this CVE.
There are currently no legacy QID mappings associated with this CVE.