CVE-2026-64247KVM: x86: hyper-v: Bound the bank index when querying sparse banks
- 8.4HighCVSS base score
- 0.15%Exploitation in 30 daysEPSS · top 95% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
Description
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: <TASK> 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 </TASK> 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 >ffff88811ba5f580: 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]
Timeline
ID reserved
By Linux
- 5 days later
· 5 days later
Published
- 3 months later
· 3 months later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| LinuxCNA (assigner) | 3.1 | High8.4 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:H |
| NVDNVD · Modified | 3.1 | High8.4 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:H |
- EPSS (exploitation in 30 days)
- 0.15% · top 95% of all CVEs (15 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: no · Technical impact: partial
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 8.4.
Affected products
- affected c58a318f6090efe06e6702b8882e2026f44f620e – < d18756b12aab30d07794446445c93112e5c69a2e
- affected c58a318f6090efe06e6702b8882e2026f44f620e – < 83c2f52c6a78b1590034e955cff3fe0b052fe4ae
- affected c58a318f6090efe06e6702b8882e2026f44f620e – < e36095d8d922bb26ce860231aacf0cd14edea07c
- affected c58a318f6090efe06e6702b8882e2026f44f620e – < f636cf6a1e7b7f40d48d8d08bd5f152aa61dd130
- affected c58a318f6090efe06e6702b8882e2026f44f620e – < 4721f8160f17554b003e8928bb61e6c9b2fe92a3
- affected 6.2
- unaffected < 6.2
- unaffected 6.6.144 – ≤ 6.6.*
- unaffected 6.12.95 – ≤ 6.12.*
- unaffected 6.18.38 – ≤ 6.18.*
- unaffected 7.1.3 – ≤ 7.1.*
- unaffected 7.2 – ≤ *
References
References5
- https://git.kernel.org/stable/c/d18756b12aab30d07794446445c93112e5c69a2e (opens in a new tab)
- https://git.kernel.org/stable/c/83c2f52c6a78b1590034e955cff3fe0b052fe4ae (opens in a new tab)
- https://git.kernel.org/stable/c/e36095d8d922bb26ce860231aacf0cd14edea07c (opens in a new tab)
- https://git.kernel.org/stable/c/f636cf6a1e7b7f40d48d8d08bd5f152aa61dd130 (opens in a new tab)
- https://git.kernel.org/stable/c/4721f8160f17554b003e8928bb61e6c9b2fe92a3 (opens in a new tab)
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2026-48656 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2026-64247)Record last updated .