CVE-2026-31787None▾ TwilightPoC availableIn 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() …
▾ Twilight zone — High severity, or a signal on a lesser flaw
impact 2.8 · likelihood 0 · exploitation 12
A public proof-of-concept already exists for this vulnerability — see Exploit availability below.
Public exploit / PoC code seen in 1 source. Availability, not in-the-wild use.
Stakeholder-Specific Vulnerability Categorization from CISA's ADP record at CVE.org: whether exploitation is observed, whether an attack can be automated, and how much of the system is at stake.
Exploit-prediction probability, daily snapshots since Nov 6.
Disclosure to exploitation, from the record and what we observed since indexing it.
Disclosed via CVEORG
Last analysed / modified upstream
0.2%
1 GitHub repo (last check)
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
Linux >= d71f513985c22f1050295d1a7e4327cf9fb060da < dbf862ce9f009128ab86b234d91413a3e450beb4Linux >= d71f513985c22f1050295d1a7e4327cf9fb060da < 2b985d3a024b9e8c24e21671b34e855569763808Linux >= d71f513985c22f1050295d1a7e4327cf9fb060da < 1576ff3869cbd3620717195f971c85b7d7fd62b5Linux >= d71f513985c22f1050295d1a7e4327cf9fb060da < 402d84ad9e89bd4cbfd07ca8598532b7021daf95Linux >= d71f513985c22f1050295d1a7e4327cf9fb060da < 2894a351fe2ea8684919d36df3188b9a35e3926fLinux >= d71f513985c22f1050295d1a7e4327cf9fb060da < 446ee446d9ae66f36e95c3c90bbcc4e56b94cde0Linux >= d71f513985c22f1050295d1a7e4327cf9fb060da < 71bf829800758a6e3889096e4754ef47ba7fc850Linux >= d71f513985c22f1050295d1a7e4327cf9fb060da < 24daca4fc07f3ff8cd0e3f629cd982187f48436aLinux 3.8Refer to the linked advisories for vendor-supplied fixes and affected version ranges.
Connected by shared product, vendor, weakness, or advisory.
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