{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2025-68810", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2025-12-24T10:30:51.047Z", "datePublished": "2026-01-13T15:29:16.475Z", "dateUpdated": "2026-01-13T15:29:16.475Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-01-13T15:29:16.475Z"}, "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't support\ntoggling KVM_MEM_GUEST_MEMFD on existing memslots. KVM prevents enabling\nKVM_MEM_GUEST_MEMFD, but doesn't 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 <TASK>\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 </TASK>\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"}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["virt/kvm/kvm_main.c"], "versions": [{"version": "a7800aa80ea4d5356b8474c2302812e9d4926fa6", "lessThan": "89dbbe6ff323fc34659621a577fe0af913f47386", "status": "affected", "versionType": "git"}, {"version": "a7800aa80ea4d5356b8474c2302812e9d4926fa6", "lessThan": "cb51bef465d8ec60a968507330e01020e35dc127", "status": "affected", "versionType": "git"}, {"version": "a7800aa80ea4d5356b8474c2302812e9d4926fa6", "lessThan": "9935df5333aa503a18de5071f53762b65c783c4c", "status": "affected", "versionType": "git"}]}, {"product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["virt/kvm/kvm_main.c"], "versions": [{"version": "6.8", "status": "affected"}, {"version": "0", "lessThan": "6.8", "status": "unaffected", "versionType": "semver"}, {"version": "6.12.64", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.18.3", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.19-rc2", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix"}]}], "cpeApplicability": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.8", "versionEndExcluding": "6.12.64"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.8", "versionEndExcluding": "6.18.3"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.8", "versionEndExcluding": "6.19-rc2"}]}]}], "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"}}}}

{}

{"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't support\ntoggling KVM_MEM_GUEST_MEMFD on existing memslots. KVM prevents enabling\nKVM_MEM_GUEST_MEMFD, but doesn't 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 <TASK>\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 </TASK>\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"}], "id": "CVE-2025-68810", "lastModified": "2026-01-13T16:16:03.190", "metrics": {}, "published": "2026-01-13T16:16:03.190", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "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"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Received"}

{}

{}