{"id":"CVE-2026-89593","summary":"hugetlb: only adjust reservation during unmapping if mapcount is 0","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nhugetlb: only adjust reservation during unmapping if mapcount is 0\n\nSince df7a6d1f6405, __unmap_hugepage_range can adjust reservations.  In\nthe case of folio mapped in both a parent and a child, if the parent\nunmaps the range first, the reservation adjustment will result in an\nunderflow of the reserved count.  Once the child unmaps the range, the\ncount is restored.  Change __unmap_hugepage_range() to check the mapcount\nbefore adjusting the reservation.","modified":"2026-09-14T03:46:18.082800316Z","published":"2026-09-11T19:44:56.557Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89593.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/0f001491e5a2ec69aa9d5dd6b799e5742245f9ea"},{"type":"WEB","url":"https://git.kernel.org/stable/c/5120b1e048d48596ffaec1a8412012a91adba73b"},{"type":"WEB","url":"https://git.kernel.org/stable/c/a3c65af20cceb7f997847727636b4017326f845d"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89593.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89593"},{"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":"df7a6d1f64056aec572162c5d35ed9ff86ece6f3"},{"fixed":"a3c65af20cceb7f997847727636b4017326f845d"},{"fixed":"0f001491e5a2ec69aa9d5dd6b799e5742245f9ea"},{"fixed":"5120b1e048d48596ffaec1a8412012a91adba73b"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-89593.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"6.9.0"},{"fixed":"6.18.50"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.2.4"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-89593.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H"}]}