{"id":"ALPINE-CVE-2026-31787","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":"2026-05-11T16:31:36.994870Z","published":"2026-04-30T11:16:21.087Z","upstream":["CVE-2026-31787"],"references":[{"type":"ADVISORY","url":"https://security.alpinelinux.org/vuln/CVE-2026-31787"}],"affected":[{"package":{"name":"xen","ecosystem":"Alpine:v3.20","purl":"pkg:apk/alpine/xen?arch=source"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0"}]}],"ecosystem_specific":{},"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/alpine/ALPINE-CVE-2026-31787.json"}},{"package":{"name":"xen","ecosystem":"Alpine:v3.21","purl":"pkg:apk/alpine/xen?arch=source"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0"}]}],"ecosystem_specific":{},"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/alpine/ALPINE-CVE-2026-31787.json"}},{"package":{"name":"xen","ecosystem":"Alpine:v3.22","purl":"pkg:apk/alpine/xen?arch=source"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0"}]}],"ecosystem_specific":{},"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/alpine/ALPINE-CVE-2026-31787.json"}},{"package":{"name":"xen","ecosystem":"Alpine:v3.23","purl":"pkg:apk/alpine/xen?arch=source"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0"}]}],"ecosystem_specific":{},"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/alpine/ALPINE-CVE-2026-31787.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"}]}