{
  "affected": [
    {
      "ecosystem_specific": {
        "urgency": "not yet assigned"
      },
      "package": {
        "ecosystem": "Debian:13",
        "name": "linux"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "6.12.95-1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "ecosystem_specific": {
        "urgency": "not yet assigned"
      },
      "package": {
        "ecosystem": "Debian:14",
        "name": "linux"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "7.1.3-1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "details": "In the Linux kernel, the following vulnerability has been resolved:  KVM: x86: hyper-v: Bound the bank index when querying sparse banks  When checking if a VP ID is included in a sparse bank set, explicitly check that the ID can actually be contained in a sparse bank (the TLFS allows for a maximum of 64 banks of 64 vCPUs each).  When handling a paravirtual TLB flush for L2, the VP ID is copied verbatim from the enlightened VMCS, without any bounds check, i.e. isn't guaranteed to be under the limit of 4096.  Failure to check the bounds of the VP ID leads to an out-of-bounds read when testing the sparse bank, and super strictly speaking could lead to KVM performing an unnecessary TLB flush for an L2 vCPU.    ==================================================================   BUG: KASAN: use-after-free in hv_is_vp_in_sparse_set+0x85/0x100 [kvm]   Read of size 8 at addr ffff88811ba5f598 by task hyperv_evmcs/2802    CPU: 12 UID: 1000 PID: 2802 Comm: hyperv_evmcs Not tainted 7.1.0-rc2 #7 PREEMPT   Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015   Call Trace:    \u003cTASK\u003e    dump_stack_lvl+0x51/0x60    print_report+0xcb/0x5d0    kasan_report+0xb4/0xe0    kasan_check_range+0x35/0x1b0    hv_is_vp_in_sparse_set+0x85/0x100 [kvm]    kvm_hv_flush_tlb+0xe9e/0x16c0 [kvm]    kvm_hv_hypercall+0xe6b/0x1e60 [kvm]    vmx_handle_exit+0x485/0x1b60 [kvm_intel]    kvm_arch_vcpu_ioctl_run+0x22e3/0x5070 [kvm]    kvm_vcpu_ioctl+0x5d0/0x10c0 [kvm]    __x64_sys_ioctl+0x129/0x1a0    do_syscall_64+0xb9/0xcf0    entry_SYSCALL_64_after_hwframe+0x4b/0x53   RIP: 0033:0x7f0e62d1a9bf    \u003c/TASK\u003e    The buggy address belongs to the physical page:   page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffffffffffffffff pfn:0x11ba5f   flags: 0x4000000000000000(zone=1)   raw: 4000000000000000 0000000000000000 00000000ffffffff 0000000000000000   raw: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000000   page dumped because: kasan: bad access detected    Memory state around the buggy address:    ffff88811ba5f480: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff    ffff88811ba5f500: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff   \u003effff88811ba5f580: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff                               ^    ffff88811ba5f600: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff    ffff88811ba5f680: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff   ==================================================================   Disabling lock debugging due to kernel taint  Opportunistically add a compile time assertion to ensure the maximum number of sparse banks exactly matches the number of possible bits in the passed in mask.  [sean: add KASAN splat, drop comment, add assert, massage changelog]",
  "id": "DEBIAN-CVE-2026-64247",
  "modified": "2026-09-14T16:47:40.598042891Z",
  "published": "2026-07-24T16:16:54.147Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://security-tracker.debian.org/tracker/CVE-2026-64247"
    }
  ],
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:H",
      "type": "CVSS_V3"
    }
  ],
  "upstream": [
    "CVE-2026-64247"
  ]
}