CVE-2025-68810 (GCVE-0-2025-68810)

Vulnerability from cvelistv5 – Published: 2026-01-13 15:29 – Updated: 2026-05-11 21:53
VLAI
Title
KVM: Disallow toggling KVM_MEM_GUEST_MEMFD on an existing memslot
Summary
In the Linux kernel, the following vulnerability has been resolved: KVM: Disallow toggling KVM_MEM_GUEST_MEMFD on an existing memslot Reject attempts to disable KVM_MEM_GUEST_MEMFD on a memslot that was initially created with a guest_memfd binding, as KVM doesn't support toggling KVM_MEM_GUEST_MEMFD on existing memslots. KVM prevents enabling KVM_MEM_GUEST_MEMFD, but doesn't prevent clearing the flag. Failure to reject the new memslot results in a use-after-free due to KVM not unbinding from the guest_memfd instance. Unbinding on a FLAGS_ONLY change is easy enough, and can/will be done as a hardening measure (in anticipation of KVM supporting dirty logging on guest_memfd at some point), but fixing the use-after-free would only address the immediate symptom. ================================================================== BUG: KASAN: slab-use-after-free in kvm_gmem_release+0x362/0x400 [kvm] Write of size 8 at addr ffff8881111ae908 by task repro/745 CPU: 7 UID: 1000 PID: 745 Comm: repro Not tainted 6.18.0-rc6-115d5de2eef3-next-kasan #3 NONE 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/0x5c0 kasan_report+0xb4/0xe0 kvm_gmem_release+0x362/0x400 [kvm] __fput+0x2fa/0x9d0 task_work_run+0x12c/0x200 do_exit+0x6ae/0x2100 do_group_exit+0xa8/0x230 __x64_sys_exit_group+0x3a/0x50 x64_sys_call+0x737/0x740 do_syscall_64+0x5b/0x900 entry_SYSCALL_64_after_hwframe+0x4b/0x53 RIP: 0033:0x7f581f2eac31 </TASK> Allocated by task 745 on cpu 6 at 9.746971s: kasan_save_stack+0x20/0x40 kasan_save_track+0x13/0x50 __kasan_kmalloc+0x77/0x90 kvm_set_memory_region.part.0+0x652/0x1110 [kvm] kvm_vm_ioctl+0x14b0/0x3290 [kvm] __x64_sys_ioctl+0x129/0x1a0 do_syscall_64+0x5b/0x900 entry_SYSCALL_64_after_hwframe+0x4b/0x53 Freed by task 745 on cpu 6 at 9.747467s: kasan_save_stack+0x20/0x40 kasan_save_track+0x13/0x50 __kasan_save_free_info+0x37/0x50 __kasan_slab_free+0x3b/0x60 kfree+0xf5/0x440 kvm_set_memslot+0x3c2/0x1160 [kvm] kvm_set_memory_region.part.0+0x86a/0x1110 [kvm] kvm_vm_ioctl+0x14b0/0x3290 [kvm] __x64_sys_ioctl+0x129/0x1a0 do_syscall_64+0x5b/0x900 entry_SYSCALL_64_after_hwframe+0x4b/0x53
Severity
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: a7800aa80ea4d5356b8474c2302812e9d4926fa6 , < 89dbbe6ff323fc34659621a577fe0af913f47386 (git)
Affected: a7800aa80ea4d5356b8474c2302812e9d4926fa6 , < cb51bef465d8ec60a968507330e01020e35dc127 (git)
Affected: a7800aa80ea4d5356b8474c2302812e9d4926fa6 , < 9935df5333aa503a18de5071f53762b65c783c4c (git)
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Linux Linux Affected: 6.8
Unaffected: 0 , < 6.8 (semver)
Unaffected: 6.12.64 , ≤ 6.12.* (semver)
Unaffected: 6.18.3 , ≤ 6.18.* (semver)
Unaffected: 6.19 , ≤ * (original_commit_for_fix)
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "virt/kvm/kvm_main.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "89dbbe6ff323fc34659621a577fe0af913f47386",
              "status": "affected",
              "version": "a7800aa80ea4d5356b8474c2302812e9d4926fa6",
              "versionType": "git"
            },
            {
              "lessThan": "cb51bef465d8ec60a968507330e01020e35dc127",
              "status": "affected",
              "version": "a7800aa80ea4d5356b8474c2302812e9d4926fa6",
              "versionType": "git"
            },
            {
              "lessThan": "9935df5333aa503a18de5071f53762b65c783c4c",
              "status": "affected",
              "version": "a7800aa80ea4d5356b8474c2302812e9d4926fa6",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "virt/kvm/kvm_main.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.8"
            },
            {
              "lessThan": "6.8",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.64",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.3",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "6.19",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.64",
                  "versionStartIncluding": "6.8",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.3",
                  "versionStartIncluding": "6.8",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.19",
                  "versionStartIncluding": "6.8",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: Disallow toggling KVM_MEM_GUEST_MEMFD on an existing memslot\n\nReject attempts to disable KVM_MEM_GUEST_MEMFD on a memslot that was\ninitially created with a guest_memfd binding, as KVM doesn\u0027t support\ntoggling KVM_MEM_GUEST_MEMFD on existing memslots.  KVM prevents enabling\nKVM_MEM_GUEST_MEMFD, but doesn\u0027t prevent clearing the flag.\n\nFailure to reject the new memslot results in a use-after-free due to KVM\nnot unbinding from the guest_memfd instance.  Unbinding on a FLAGS_ONLY\nchange is easy enough, and can/will be done as a hardening measure (in\nanticipation of KVM supporting dirty logging on guest_memfd at some point),\nbut fixing the use-after-free would only address the immediate symptom.\n\n  ==================================================================\n  BUG: KASAN: slab-use-after-free in kvm_gmem_release+0x362/0x400 [kvm]\n  Write of size 8 at addr ffff8881111ae908 by task repro/745\n\n  CPU: 7 UID: 1000 PID: 745 Comm: repro Not tainted 6.18.0-rc6-115d5de2eef3-next-kasan #3 NONE\n  Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015\n  Call Trace:\n   \u003cTASK\u003e\n   dump_stack_lvl+0x51/0x60\n   print_report+0xcb/0x5c0\n   kasan_report+0xb4/0xe0\n   kvm_gmem_release+0x362/0x400 [kvm]\n   __fput+0x2fa/0x9d0\n   task_work_run+0x12c/0x200\n   do_exit+0x6ae/0x2100\n   do_group_exit+0xa8/0x230\n   __x64_sys_exit_group+0x3a/0x50\n   x64_sys_call+0x737/0x740\n   do_syscall_64+0x5b/0x900\n   entry_SYSCALL_64_after_hwframe+0x4b/0x53\n  RIP: 0033:0x7f581f2eac31\n   \u003c/TASK\u003e\n\n  Allocated by task 745 on cpu 6 at 9.746971s:\n   kasan_save_stack+0x20/0x40\n   kasan_save_track+0x13/0x50\n   __kasan_kmalloc+0x77/0x90\n   kvm_set_memory_region.part.0+0x652/0x1110 [kvm]\n   kvm_vm_ioctl+0x14b0/0x3290 [kvm]\n   __x64_sys_ioctl+0x129/0x1a0\n   do_syscall_64+0x5b/0x900\n   entry_SYSCALL_64_after_hwframe+0x4b/0x53\n\n  Freed by task 745 on cpu 6 at 9.747467s:\n   kasan_save_stack+0x20/0x40\n   kasan_save_track+0x13/0x50\n   __kasan_save_free_info+0x37/0x50\n   __kasan_slab_free+0x3b/0x60\n   kfree+0xf5/0x440\n   kvm_set_memslot+0x3c2/0x1160 [kvm]\n   kvm_set_memory_region.part.0+0x86a/0x1110 [kvm]\n   kvm_vm_ioctl+0x14b0/0x3290 [kvm]\n   __x64_sys_ioctl+0x129/0x1a0\n   do_syscall_64+0x5b/0x900\n   entry_SYSCALL_64_after_hwframe+0x4b/0x53"
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-05-11T21:53:46.835Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/89dbbe6ff323fc34659621a577fe0af913f47386"
        },
        {
          "url": "https://git.kernel.org/stable/c/cb51bef465d8ec60a968507330e01020e35dc127"
        },
        {
          "url": "https://git.kernel.org/stable/c/9935df5333aa503a18de5071f53762b65c783c4c"
        }
      ],
      "title": "KVM: Disallow toggling KVM_MEM_GUEST_MEMFD on an existing memslot",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2025-68810",
    "datePublished": "2026-01-13T15:29:16.475Z",
    "dateReserved": "2025-12-24T10:30:51.047Z",
    "dateUpdated": "2026-05-11T21:53:46.835Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2025-68810",
      "date": "2026-06-29",
      "epss": "0.00166",
      "percentile": "0.06193"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2025-68810\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2026-01-13T16:16:03.190\",\"lastModified\":\"2026-06-17T09:59:39.210\",\"vulnStatus\":\"Deferred\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nKVM: Disallow toggling KVM_MEM_GUEST_MEMFD on an existing memslot\\n\\nReject attempts to disable KVM_MEM_GUEST_MEMFD on a memslot that was\\ninitially created with a guest_memfd binding, as KVM doesn\u0027t support\\ntoggling KVM_MEM_GUEST_MEMFD on existing memslots.  KVM prevents enabling\\nKVM_MEM_GUEST_MEMFD, but doesn\u0027t prevent clearing the flag.\\n\\nFailure to reject the new memslot results in a use-after-free due to KVM\\nnot unbinding from the guest_memfd instance.  Unbinding on a FLAGS_ONLY\\nchange is easy enough, and can/will be done as a hardening measure (in\\nanticipation of KVM supporting dirty logging on guest_memfd at some point),\\nbut fixing the use-after-free would only address the immediate symptom.\\n\\n  ==================================================================\\n  BUG: KASAN: slab-use-after-free in kvm_gmem_release+0x362/0x400 [kvm]\\n  Write of size 8 at addr ffff8881111ae908 by task repro/745\\n\\n  CPU: 7 UID: 1000 PID: 745 Comm: repro Not tainted 6.18.0-rc6-115d5de2eef3-next-kasan #3 NONE\\n  Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015\\n  Call Trace:\\n   \u003cTASK\u003e\\n   dump_stack_lvl+0x51/0x60\\n   print_report+0xcb/0x5c0\\n   kasan_report+0xb4/0xe0\\n   kvm_gmem_release+0x362/0x400 [kvm]\\n   __fput+0x2fa/0x9d0\\n   task_work_run+0x12c/0x200\\n   do_exit+0x6ae/0x2100\\n   do_group_exit+0xa8/0x230\\n   __x64_sys_exit_group+0x3a/0x50\\n   x64_sys_call+0x737/0x740\\n   do_syscall_64+0x5b/0x900\\n   entry_SYSCALL_64_after_hwframe+0x4b/0x53\\n  RIP: 0033:0x7f581f2eac31\\n   \u003c/TASK\u003e\\n\\n  Allocated by task 745 on cpu 6 at 9.746971s:\\n   kasan_save_stack+0x20/0x40\\n   kasan_save_track+0x13/0x50\\n   __kasan_kmalloc+0x77/0x90\\n   kvm_set_memory_region.part.0+0x652/0x1110 [kvm]\\n   kvm_vm_ioctl+0x14b0/0x3290 [kvm]\\n   __x64_sys_ioctl+0x129/0x1a0\\n   do_syscall_64+0x5b/0x900\\n   entry_SYSCALL_64_after_hwframe+0x4b/0x53\\n\\n  Freed by task 745 on cpu 6 at 9.747467s:\\n   kasan_save_stack+0x20/0x40\\n   kasan_save_track+0x13/0x50\\n   __kasan_save_free_info+0x37/0x50\\n   __kasan_slab_free+0x3b/0x60\\n   kfree+0xf5/0x440\\n   kvm_set_memslot+0x3c2/0x1160 [kvm]\\n   kvm_set_memory_region.part.0+0x86a/0x1110 [kvm]\\n   kvm_vm_ioctl+0x14b0/0x3290 [kvm]\\n   __x64_sys_ioctl+0x129/0x1a0\\n   do_syscall_64+0x5b/0x900\\n   entry_SYSCALL_64_after_hwframe+0x4b/0x53\"},{\"lang\":\"es\",\"value\":\"En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\\n\\nKVM: No permitir la alternancia de KVM_MEM_GUEST_MEMFD en un memslot existente\\n\\nRechazar los intentos de deshabilitar KVM_MEM_GUEST_MEMFD en un memslot que fue creado inicialmente con una vinculaci\u00f3n guest_memfd, ya que KVM no soporta la alternancia de KVM_MEM_GUEST_MEMFD en memslots existentes. KVM impide habilitar KVM_MEM_GUEST_MEMFD, pero no impide borrar el indicador.\\n\\nLa falta de rechazo del nuevo memslot resulta en un uso despu\u00e9s de liberaci\u00f3n debido a que KVM no se desvincula de la instancia guest_memfd. La desvinculaci\u00f3n en un cambio de FLAGS_ONLY es bastante sencilla, y puede/ser\u00e1 realizada como una medida de endurecimiento (en anticipaci\u00f3n de que KVM soporte el registro de cambios (dirty logging) en guest_memfd en alg\u00fan momento), pero corregir el uso despu\u00e9s de liberaci\u00f3n solo abordar\u00eda el s\u00edntoma inmediato.\\n\\n  ==================================================================\\n  ERROR: KASAN: uso despu\u00e9s de liberaci\u00f3n de slab en kvm_gmem_release+0x362/0x400 [kvm]\\n  Escritura de tama\u00f1o 8 en la direcci\u00f3n ffff8881111ae908 por la tarea repro/745\\n\\n  CPU: 7 UID: 1000 PID: 745 Comm: repro No contaminado 6.18.0-rc6-115d5de2eef3-next-kasan #3 NINGUNO\\n  Nombre del hardware: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015\\n  Traza de llamada:\\n   \\n   dump_stack_lvl+0x51/0x60\\n   print_report+0xcb/0x5c0\\n   kasan_report+0xb4/0xe0\\n   kvm_gmem_release+0x362/0x400 [kvm]\\n   __fput+0x2fa/0x9d0\\n   task_work_run+0x12c/0x200\\n   do_exit+0x6ae/0x2100\\n   do_group_exit+0xa8/0x230\\n   __x64_sys_exit_group+0x3a/0x50\\n   x64_sys_call+0x737/0x740\\n   do_syscall_64+0x5b/0x900\\n   entry_SYSCALL_64_after_hwframe+0x4b/0x53\\n  RIP: 0033:0x7f581f2eac31\\n   \\n\\n  Asignado por la tarea 745 en la CPU 6 a las 9.746971s:\\n   kasan_save_stack+0x20/0x40\\n   kasan_save_track+0x13/0x50\\n   __kasan_kmalloc+0x77/0x90\\n   kvm_set_memory_region.part.0+0x652/0x1110 [kvm]\\n   kvm_vm_ioctl+0x14b0/0x3290 [kvm]\\n   __x64_sys_ioctl+0x129/0x1a0\\n   do_syscall_64+0x5b/0x900\\n   entry_SYSCALL_64_after_hwframe+0x4b/0x53\\n\\n  Liberado por la tarea 745 en la CPU 6 a las 9.747467s:\\n   kasan_save_stack+0x20/0x40\\n   kasan_save_track+0x13/0x50\\n   __kasan_save_free_info+0x37/0x50\\n   __kasan_slab_free+0x3b/0x60\\n   kfree+0xf5/0x440\\n   kvm_set_memslot+0x3c2/0x1160 [kvm]\\n   kvm_set_memory_region.part.0+0x86a/0x1110 [kvm]\\n   kvm_vm_ioctl+0x14b0/0x3290 [kvm]\\n   __x64_sys_ioctl+0x129/0x1a0\\n   do_syscall_64+0x5b/0x900\\n   entry_SYSCALL_64_after_hwframe+0x4b/0x53\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"virt/kvm/kvm_main.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"a7800aa80ea4d5356b8474c2302812e9d4926fa6\",\"lessThan\":\"89dbbe6ff323fc34659621a577fe0af913f47386\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"a7800aa80ea4d5356b8474c2302812e9d4926fa6\",\"lessThan\":\"cb51bef465d8ec60a968507330e01020e35dc127\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"a7800aa80ea4d5356b8474c2302812e9d4926fa6\",\"lessThan\":\"9935df5333aa503a18de5071f53762b65c783c4c\",\"versionType\":\"git\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"virt/kvm/kvm_main.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"6.8\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"6.8\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.12.64\",\"lessThanOrEqual\":\"6.12.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.18.3\",\"lessThanOrEqual\":\"6.18.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.19\",\"lessThanOrEqual\":\"*\",\"versionType\":\"original_commit_for_fix\",\"status\":\"unaffected\"}]}]}],\"metrics\":{},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/89dbbe6ff323fc34659621a577fe0af913f47386\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/9935df5333aa503a18de5071f53762b65c783c4c\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/cb51bef465d8ec60a968507330e01020e35dc127\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}"
  }
}


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