{"id":"CVE-2026-31787","summary":"xen/privcmd: fix double free via VMA splitting","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nxen/privcmd: fix double free via VMA splitting\n\nprivcmd_vm_ops defines .close (privcmd_close), but neither .may_split\nnor .open. When userspace does a partial munmap() on a privcmd mapping,\nthe kernel splits the VMA via __split_vma(). Since may_split is NULL,\nthe split is allowed. vm_area_dup() copies vm_private_data (a pages\narray allocated in alloc_empty_pages()) into the new VMA without any\nfixup, because there is no .open callback.\n\nBoth VMAs now point to the same pages array. When the unmapped portion\nis closed, privcmd_close() calls:\n    - xen_unmap_domain_gfn_range()\n    - xen_free_unpopulated_pages()\n    - kvfree(pages)\n\nThe surviving VMA still holds the dangling pointer. When it is later\ndestroyed, the same sequence runs again, which leads to a double free.\n\nFix this issue by adding a .may_split callback denying the VMA split.\n\nThis is XSA-487 / CVE-2026-31787","modified":"2026-05-18T05:59:54.860221778Z","published":"2026-04-30T10:31:28.992Z","related":["CGA-cx2m-89f9-7g8q","openSUSE-SU-2026:10703-1"],"database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/31xxx/CVE-2026-31787.json"},"references":[{"type":"WEB","url":"http://www.openwall.com/lists/oss-security/2026/04/28/14"},{"type":"WEB","url":"https://git.kernel.org/stable/c/1576ff3869cbd3620717195f971c85b7d7fd62b5"},{"type":"WEB","url":"https://git.kernel.org/stable/c/24daca4fc07f3ff8cd0e3f629cd982187f48436a"},{"type":"WEB","url":"https://git.kernel.org/stable/c/2894a351fe2ea8684919d36df3188b9a35e3926f"},{"type":"WEB","url":"https://git.kernel.org/stable/c/2b985d3a024b9e8c24e21671b34e855569763808"},{"type":"WEB","url":"https://git.kernel.org/stable/c/402d84ad9e89bd4cbfd07ca8598532b7021daf95"},{"type":"WEB","url":"https://git.kernel.org/stable/c/446ee446d9ae66f36e95c3c90bbcc4e56b94cde0"},{"type":"WEB","url":"https://git.kernel.org/stable/c/71bf829800758a6e3889096e4754ef47ba7fc850"},{"type":"WEB","url":"https://git.kernel.org/stable/c/dbf862ce9f009128ab86b234d91413a3e450beb4"},{"type":"ADVISORY","url":"http://xenbits.xen.org/xsa/advisory-487.html"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/31xxx/CVE-2026-31787.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-31787"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"d71f513985c22f1050295d1a7e4327cf9fb060da"},{"fixed":"dbf862ce9f009128ab86b234d91413a3e450beb4"},{"fixed":"2b985d3a024b9e8c24e21671b34e855569763808"},{"fixed":"1576ff3869cbd3620717195f971c85b7d7fd62b5"},{"fixed":"402d84ad9e89bd4cbfd07ca8598532b7021daf95"},{"fixed":"2894a351fe2ea8684919d36df3188b9a35e3926f"},{"fixed":"446ee446d9ae66f36e95c3c90bbcc4e56b94cde0"},{"fixed":"71bf829800758a6e3889096e4754ef47ba7fc850"},{"fixed":"24daca4fc07f3ff8cd0e3f629cd982187f48436a"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-31787.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"3.8.0"},{"fixed":"5.10.254"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.11.0"},{"fixed":"5.15.204"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.16.0"},{"fixed":"6.1.170"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.137"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.85"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.26"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.0.3"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-31787.json"}}],"schema_version":"1.7.5"}