{"id":"CVE-2026-64247","revision":null,"records":[{"revision":"c67cb3a6609940aca09c4badfa7702ea","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-64247","aliases":[],"title":"KVM: x86: hyper-v: Bound the bank index when querying sparse banks","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: x86: hyper-v: Bound the bank index when querying sparse banks\n\nWhen checking if a VP ID is included in a sparse bank set, explicitly check\nthat the ID can actually be contained in a sparse bank (the TLFS allows for\na maximum of 64 banks of 64 vCPUs each). When handling a paravirtual TLB\nflush for L2, the VP ID is copied verbatim from the enlightened VMCS,\nwithout any bounds check, i.e. isn't guaranteed to be under the limit of\n4096.\n\nFailure to check the bounds of the VP ID leads to an out-of-bounds read\nwhen testing the sparse bank, and super strictly speaking could lead to KVM\nperforming an unnecessary TLB flush for an L2 vCPU.\n\n ==================================================================\n BUG: KASAN: use-after-free in hv_is_vp_in_sparse_set+0x85/0x100 [kvm]\n Read of size 8 at addr ffff88811ba5f598 by task hyperv_evmcs/2802\n\n CPU: 12 UID: 1000 PID: 2802 Comm: hyperv_evmcs Not tainted 7.1.0-rc2 #7 PREEMPT\n Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015\n Call Trace:\n \n dump_stack_lvl+0x51/0x60\n print_report+0xcb/0x5d0\n kasan_report+0xb4/0xe0\n kasan_check_range+0x35/0x1b0\n hv_is_vp_in_sparse_set+0x85/0x100 [kvm]\n kvm_hv_flush_tlb+0xe9e/0x16c0 [kvm]\n kvm_hv_hypercall+0xe6b/0x1e60 [kvm]\n vmx_handle_exit+0x485/0x1b60 [kvm_intel]\n kvm_arch_vcpu_ioctl_run+0x22e3/0x5070 [kvm]\n kvm_vcpu_ioctl+0x5d0/0x10c0 [kvm]\n __x64_sys_ioctl+0x129/0x1a0\n do_syscall_64+0xb9/0xcf0\n entry_SYSCALL_64_after_hwframe+0x4b/0x53\n RIP: 0033:0x7f0e62d1a9bf\n \n\n The buggy address belongs to the physical page:\n page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffffffffffffffff pfn:0x11ba5f\n flags: 0x4000000000000000(zone=1)\n raw: 4000000000000000 0000000000000000 00000000ffffffff 0000000000000000\n raw: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000000\n page dumped because: kasan: bad access detected\n\n Memory state around the buggy address:\n ffff88811ba5f480: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff\n ffff88811ba5f500: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff\n >ffff88811ba5f580: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff\n ^\n ffff88811ba5f600: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff\n ffff88811ba5f680: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff\n ==================================================================\n Disabling lock debugging due to kernel taint\n\nOpportunistically add a compile time assertion to ensure the maximum number\nof sparse banks exactly matches the number of possible bits in the passed\nin mask.\n\n[sean: add KASAN splat, drop comment, add assert, massage changelog]","state":0,"publishedAt":"2026-07-24T15:31:15.304+00:00","modifiedAt":"2026-10-19T20:28:16.498+00:00","affected":[{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n \"product\": \"Linux\",\n \"vendor\": \"Linux\",\n \"defaultStatus\": \"unaffected\",\n \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n \"programFiles\": [\n \"arch/x86/kvm/hyperv.c\"\n ],\n \"versions\": [\n {\n \"version\": \"c58a318f6090efe06e6702b8882e2026f44f620e\",\n \"lessThan\": \"d18756b12aab30d07794446445c93112e5c69a2e\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"c58a318f6090efe06e6702b8882e2026f44f620e\",\n \"lessThan\": \"83c2f52c6a78b1590034e955cff3fe0b052fe4ae\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"c58a318f6090efe06e6702b8882e2026f44f620e\",\n \"lessThan\": \"e36095d8d922bb26ce860231aacf0cd14edea07c\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"c58a318f6090efe06e6702b8882e2026f44f620e\",\n \"lessThan\": \"f636cf6a1e7b7f40d48d8d08bd5f152aa61dd130\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"c58a318f6090efe06e6702b8882e2026f44f620e\",\n \"lessThan\": \"4721f8160f17554b003e8928bb61e6c9b2fe92a3\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n }\n ]\n }"},{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n \"product\": \"Linux\",\n \"vendor\": \"Linux\",\n \"defaultStatus\": \"affected\",\n \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n \"programFiles\": [\n \"arch/x86/kvm/hyperv.c\"\n ],\n \"versions\": [\n {\n \"version\": \"6.2\",\n \"status\": \"affected\"\n },\n {\n \"version\": \"0\",\n \"lessThan\": \"6.2\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.6.144\",\n \"lessThanOrEqual\": \"6.6.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.12.95\",\n \"lessThanOrEqual\": \"6.12.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.18.38\",\n \"lessThanOrEqual\": \"6.18.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"7.1.3\",\n \"lessThanOrEqual\": \"7.1.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"7.2\",\n \"lessThanOrEqual\": \"*\",\n \"status\": \"unaffected\",\n \"versionType\": \"original_commit_for_fix\"\n }\n ]\n }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:H","score":8.4,"severity":"HIGH"}],"references":["https://git.kernel.org/stable/c/d18756b12aab30d07794446445c93112e5c69a2e","https://git.kernel.org/stable/c/83c2f52c6a78b1590034e955cff3fe0b052fe4ae","https://git.kernel.org/stable/c/e36095d8d922bb26ce860231aacf0cd14edea07c","https://git.kernel.org/stable/c/f636cf6a1e7b7f40d48d8d08bd5f152aa61dd130","https://git.kernel.org/stable/c/4721f8160f17554b003e8928bb61e6c9b2fe92a3"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-64247","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-64247","identifiers":["CVE-2026-64247"]},"retained":false,"historicalAffected":[]}],"coverage":[{"source":"cisa-kev:global","scope":"Complete CISA KEV catalog; all vendors. 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Not a global EPSS backfill.","generation":"2026-11-08T18:47:41.4173610+00:00","complete":true,"records":1096,"lastAttemptAt":"2026-11-08T18:47:41.417361+00:00","lastSuccessAt":"2026-11-08T18:47:41.7296264+00:00","error":null,"lastVerifiedAt":"2026-11-08T18:47:41.7296273+00:00","snapshotPublishedAt":null,"importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"nvd","scope":"Rolling NVD lookups of CVE aliases in current public OSV archives; 500 identifiers per refresh, rechecked after 48 hours. Not a global NVD catalog. Successful not-found lookups count as checked; they do not imply withdrawal or safety. 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