cbcvebase.
CVE-2025-68810
published 2026-01-13

CVE-2025-68810: In the Linux kernel, the following vulnerability has been resolved: KVM: Disallow toggling KVM_MEM_GUEST_MEMFD on an existing memslot Reject attempts to…

PriorityP340high7.8CVSS 3.1
AVLACLPRLUINSUCHIHAH
EPSS
0.12%
2.5th percentile
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: 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 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+0

Affected

38 ranges· showing 25
VendorProductVersion rangeFixed in
debianlinux< linux 6.18.3-1 (forky)linux 6.18.3-1 (forky)
linuxlinux
linuxlinux>= a7800aa80ea4d5356b8474c2302812e9d4926fa6 < 89dbbe6ff323fc34659621a577fe0af913f4738689dbbe6ff323fc34659621a577fe0af913f47386
linuxlinux>= a7800aa80ea4d5356b8474c2302812e9d4926fa6 < cb51bef465d8ec60a968507330e01020e35dc127cb51bef465d8ec60a968507330e01020e35dc127
linuxlinux>= a7800aa80ea4d5356b8474c2302812e9d4926fa6 < 9935df5333aa503a18de5071f53762b65c783c4c9935df5333aa503a18de5071f53762b65c783c4c
linuxlinux_kernel>= 0 < 6.12.69-16.12.69-1
linuxlinux_kernel>= 0 < 6.18.3-16.18.3-1
linuxlinux_kernel>= 6.13.0 < 6.18.36.18.3
linuxlinux_kernel>= 6.8.0 < 6.12.646.12.64
ubuntulinux-aws
ubuntulinux-aws-6.17
ubuntulinux-aws-fips
ubuntulinux-azure
ubuntulinux-azure-6.17
ubuntulinux-azure-6.8
ubuntulinux-azure-fips
ubuntulinux-fips
ubuntulinux-gcp
ubuntulinux-gcp-6.17
ubuntulinux-gcp-6.8
ubuntulinux-gcp-fips
ubuntulinux-hwe-6.17
ubuntulinux-hwe-6.8
ubuntulinux-ibm-6.8
ubuntulinux-nvidia

CVSS provenance

nvdv3.17.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
vendor_ubuntu6.4MEDIUM
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