UBUNTU-CVE-2025-68810: Use After Free

Q: Who is realistically exposed to this issue?

Systems using KVM with memslots initially created with a guest_memfd binding are exposed if a privileged local actor can modify those existing memslots. The listed affected Ubuntu kernel packages include linux-riscv, linux-realtime, linux-azure, linux-gcp, linux-azure-fde, linux-hwe-edge, linux-gke, and linux-gkeop.

Q: What does an attacker need to do to trigger the flaw?

An attacker needs high privileges and local access, then must attempt to clear KVM_MEM_GUEST_MEMFD on an existing memslot that was created with a guest_memfd binding. KVM previously blocked enabling this flag on an existing memslot but did not block disabling it.

Q: What is the impact of successful exploitation?

Clearing the flag can leave KVM bound to the guest_memfd instance and cause a use-after-free. The supplied severity vector indicates high impact to confidentiality, integrity, and availability of the vulnerable system.

Q: How can I tell whether a system is using the affected configuration?

Review KVM users for memslots created with a guest_memfd binding and for later flags-only updates that clear KVM_MEM_GUEST_MEMFD. The vulnerability is specifically tied to toggling that flag off on an existing guest_memfd-backed memslot.

Published Jan 13, 2026

Updated

In the Linux kernel, the following vulnerability has been resolved: KVM: Disallow toggling KVMMEMGUESTMEMFD on an existing memslot Reject attempts to disable KVMMEMGUESTMEMFD on a memslot that was initially created with a guestmemfd binding, as KVM doesn't support toggling KVMMEMGUESTMEMFD on existing memslots. KVM prevents enabling KVMMEMGUESTMEMFD, 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 guestmemfd instance. Unbinding on a FLAGSONLY change is easy enough, and can/will be done as a hardening measure (in anticipation of KVM supporting dirty logging on guestmemfd at some point), but fixing the use-after-free would only address the immediate symptom. ================================================================== BUG: KASAN: slab-use-after-free in kvmgmemrelease+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> dumpstacklvl+0x51/0x60 printreport+0xcb/0x5c0 kasanreport+0xb4/0xe0 kvmgmemrelease+0x362/0x400 [kvm] fput+0x2fa/0x9d0 taskworkrun+0x12c/0x200 doexit+0x6ae/0x2100 dogroupexit+0xa8/0x230 x64sysexitgroup+0x3a/0x50 x64syscall+0x737/0x740 dosyscall64+0x5b/0x900 entrySYSCALL64afterhwframe+0x4b/0x53 RIP: 0033:0x7f581f2eac31 </TASK> Allocated by task 745 on cpu 6 at 9.746971s: kasansavestack+0x20/0x40 kasansavetrack+0x13/0x50 kasankmalloc+0x77/0x90 kvmsetmemoryregion.part.0+0x652/0x1110 [kvm] kvmvmioctl+0x14b0/0x3290 [kvm] x64sysioctl+0x129/0x1a0 dosyscall64+0x5b/0x900 entrySYSCALL64afterhwframe+0x4b/0x53 Freed by task 745 on cpu 6 at 9.747467s: kasansavestack+0x20/0x40 kasansavetrack+0x13/0x50 kasansavefreeinfo+0x37/0x50 kasanslabfree+0x3b/0x60 kfree+0xf5/0x440 kvmsetmemslot+0x3c2/0x1160 [kvm] kvmsetmemoryregion.part.0+0x86a/0x1110 [kvm] kvmvmioctl+0x14b0/0x3290 [kvm] x64sysioctl+0x129/0x1a0 dosyscall64+0x5b/0x900 entrySYSCALL64afterhwframe+0x4b/0x53

Affected Software

150 affected componentsFixes available

ubuntu/linux-hwe-edge*

ubuntu/linux-aws-5.0*

ubuntu/linux-aws-5.3*

ubuntu/linux-azure*

ubuntu/linux-azure-5.3*

ubuntu/linux-azure-edge*

ubuntu/linux-gcp*

ubuntu/linux-gcp-5.3*

ubuntu/linux-gke-4.15*

ubuntu/linux-gke-5.4*

ubuntu/linux-gkeop-5.4*

ubuntu/linux-hwe*

ubuntu/linux-hwe-edge*

ubuntu/linux-oem*

ubuntu/linux-oracle-5.0*

ubuntu/linux-oracle-5.3*

ubuntu/linux-aws-5.11*

ubuntu/linux-aws-5.13*

ubuntu/linux-aws-5.8*

ubuntu/linux-azure-5.11*

ubuntu/linux-azure-5.13*

ubuntu/linux-azure-5.8*

ubuntu/linux-azure-fde*

ubuntu/linux-gcp-5.11*

ubuntu/linux-gcp-5.13*

ubuntu/linux-gcp-5.8*

ubuntu/linux-gke*

ubuntu/linux-gke-5.15*

ubuntu/linux-gkeop*

ubuntu/linux-gkeop-5.15*

ubuntu/linux-hwe-5.11*

ubuntu/linux-hwe-5.13*

ubuntu/linux-hwe-5.8*

ubuntu/linux-intel-5.13*

ubuntu/linux-oem-5.10*

ubuntu/linux-oem-5.13*

ubuntu/linux-oem-5.6*

ubuntu/linux-oracle-5.11*

ubuntu/linux-oracle-5.13*

ubuntu/linux-oracle-5.8*

ubuntu/linux-raspi2*

ubuntu/linux-riscv*

ubuntu/linux-riscv-5.11*

ubuntu/linux-riscv-5.8*

ubuntu/linux-allwinner-5.19*

ubuntu/linux-aws-5.19*

ubuntu/linux-aws-6.2*

ubuntu/linux-aws-6.5*

ubuntu/linux-aws-6.8<6.8.0-1052.55~22.04.1

6.8.0-1052.55~22.04.1

ubuntu/linux-azure-5.19*

ubuntu/linux-azure-6.2*

ubuntu/linux-azure-6.5*

ubuntu/linux-azure-6.8<6.8.0-1059.65~22.04.1

6.8.0-1059.65~22.04.1

ubuntu/linux-azure-fde-5.19*

ubuntu/linux-azure-fde-6.2*

ubuntu/linux-azure-fde-6.8<6.8.0-1058.65~22.04.1

6.8.0-1058.65~22.04.1

ubuntu/linux-gcp-5.19*

ubuntu/linux-gcp-6.2*

ubuntu/linux-gcp-6.5*

ubuntu/linux-gcp-6.8<6.8.0-1054.57~22.04.1

6.8.0-1054.57~22.04.1

ubuntu/linux-hwe-5.19*

ubuntu/linux-hwe-6.2*

ubuntu/linux-hwe-6.5*

ubuntu/linux-hwe-6.8<6.8.0-110.110~22.04.1

6.8.0-110.110~22.04.1

ubuntu/linux-ibm-6.8<6.8.0-1051.51~22.04.1

6.8.0-1051.51~22.04.1

ubuntu/linux-intel-iot-realtime*

ubuntu/linux-lowlatency-hwe-5.19*

ubuntu/linux-lowlatency-hwe-6.2*

ubuntu/linux-lowlatency-hwe-6.5*

ubuntu/linux-lowlatency-hwe-6.8<6.8.0-110.110.1~22.04.1

6.8.0-110.110.1~22.04.1

ubuntu/linux-nvidia-6.2*

ubuntu/linux-nvidia-6.5*

ubuntu/linux-nvidia-6.8<6.8.0-1051.54~22.04.1

6.8.0-1051.54~22.04.1

ubuntu/linux-oem-5.17*

ubuntu/linux-oem-6.0*

ubuntu/linux-oem-6.1*

ubuntu/linux-oem-6.5*

ubuntu/linux-oracle-6.5*

ubuntu/linux-oracle-6.8<6.8.0-1049.50~22.04.1

6.8.0-1049.50~22.04.1

ubuntu/linux-realtime*

ubuntu/linux-riscv*

ubuntu/linux-riscv-5.19*

ubuntu/linux-riscv-6.5*

ubuntu/linux-riscv-6.8<6.8.0-110.110~22.04.1

6.8.0-110.110~22.04.1

ubuntu/linux-starfive-5.19*

ubuntu/linux-starfive-6.2*

ubuntu/linux-starfive-6.5*

ubuntu/linux-realtime-6.8<6.8.1-1047.48~22.04.1

6.8.1-1047.48~22.04.1

ubuntu/linux<6.8.0-110.110

6.8.0-110.110

ubuntu/linux-aws<6.8.0-1052.55

6.8.0-1052.55

ubuntu/linux-aws-6.14*

ubuntu/linux-aws-6.17<6.17.0-1012.12~24.04.1

6.17.0-1012.12~24.04.1

ubuntu/linux-azure<6.8.0-1054.60

6.8.0-1054.60

ubuntu/linux-azure-6.11*

ubuntu/linux-azure-6.14*

ubuntu/linux-azure-6.17<6.17.0-1013.13~24.04.1

6.17.0-1013.13~24.04.1

ubuntu/linux-azure-fde<6.8.0-1058.65

6.8.0-1058.65

ubuntu/linux-azure-fde-6.14*

ubuntu/linux-azure-nvidia<6.8.0-1039.42

6.8.0-1039.42

ubuntu/linux-azure-nvidia-6.14*

ubuntu/linux-gcp<6.8.0-1054.57

6.8.0-1054.57

ubuntu/linux-gcp-6.11*

ubuntu/linux-gcp-6.14*

ubuntu/linux-gcp-6.17<6.17.0-1012.12~24.04.1

6.17.0-1012.12~24.04.1

ubuntu/linux-gke<6.8.0-1050.56

6.8.0-1050.56

ubuntu/linux-gkeop<6.8.0-1037.40

6.8.0-1037.40

ubuntu/linux-hwe-6.11*

ubuntu/linux-hwe-6.14*

ubuntu/linux-hwe-6.17<6.17.0-22.22~24.04.1

6.17.0-22.22~24.04.1

ubuntu/linux-ibm<6.8.0-1051.51

6.8.0-1051.51

ubuntu/linux-lowlatency<6.8.0-110.110.1

6.8.0-110.110.1

ubuntu/linux-lowlatency-hwe-6.11*

ubuntu/linux-nvidia<6.8.0-1051.54

6.8.0-1051.54

ubuntu/linux-nvidia-6.11*

ubuntu/linux-nvidia-6.17<6.17.0-1018.18

6.17.0-1018.18

ubuntu/linux-nvidia-lowlatency<6.8.0-1051.54.1

6.8.0-1051.54.1

ubuntu/linux-nvidia-tegra<6.8.0-1022.22

6.8.0-1022.22

ubuntu/linux-oem-6.11*

ubuntu/linux-oem-6.14*

ubuntu/linux-oem-6.17<6.17.0-1020.20

6.17.0-1020.20

ubuntu/linux-oem-6.8*

ubuntu/linux-oracle<6.8.0-1049.50

6.8.0-1049.50

ubuntu/linux-oracle-6.14*

ubuntu/linux-oracle-6.17<6.17.0-1011.11~24.04.1

6.17.0-1011.11~24.04.1

ubuntu/linux-raspi<6.8.0-1052.56

6.8.0-1052.56

ubuntu/linux-raspi-realtime*

ubuntu/linux-realtime*

ubuntu/linux-riscv*

ubuntu/linux-riscv-6.14*

ubuntu/linux-riscv-6.17<6.17.0-22.22.1~24.04.1

6.17.0-22.22.1~24.04.1

ubuntu/linux-xilinx<6.8.0-1028.29

6.8.0-1028.29

ubuntu/linux-bluefield<6.8.0-1017.21

6.8.0-1017.21

ubuntu/linux-raspi-realtime<6.8.0-2042.43

6.8.0-2042.43

ubuntu/linux-realtime<6.8.1-1047.48

6.8.1-1047.48

ubuntu/linux-realtime-6.14*

ubuntu/linux-realtime-6.17<6.17.0-1010.11~24.04.1

6.17.0-1010.11~24.04.1

ubuntu/linux-aws-fips<6.8.0-1052.55+fips1

6.8.0-1052.55+fips1

ubuntu/linux-azure-fips<6.8.0-1053.59+fips1

6.8.0-1053.59+fips1

ubuntu/linux-fips<6.8.0-110.110+fips2

6.8.0-110.110+fips2

ubuntu/linux-gcp-fips<6.8.0-1054.57+fips1

6.8.0-1054.57+fips1

ubuntu/linux<6.17.0-22.22

6.17.0-22.22

ubuntu/linux-aws<6.17.0-1012.12

6.17.0-1012.12

ubuntu/linux-azure<6.17.0-1013.13

6.17.0-1013.13

ubuntu/linux-azure-fde*

ubuntu/linux-gcp<6.17.0-1012.12

6.17.0-1012.12

ubuntu/linux-oracle<6.17.0-1011.11

6.17.0-1011.11

ubuntu/linux-raspi<6.17.0-1013.13

6.17.0-1013.13

ubuntu/linux-realtime<6.17.0-1010.11

6.17.0-1010.11

ubuntu/linux-riscv<6.17.0-22.22.1

6.17.0-22.22.1

ubuntu/linux-vmware*

Remediation

Recommended actions to resolve this vulnerability, in priority order.

Upgrade
Upgrade ubuntu/linux-aws-6.8 to a version that resolves this vulnerability.
Fixed in 6.8.0-1052.55~22.04.1
Upgrade
Upgrade ubuntu/linux-azure-6.8 to a version that resolves this vulnerability.
Fixed in 6.8.0-1059.65~22.04.1
Upgrade
Upgrade ubuntu/linux-azure-fde-6.8 to a version that resolves this vulnerability.
Fixed in 6.8.0-1058.65~22.04.1
Upgrade
Upgrade ubuntu/linux-gcp-6.8 to a version that resolves this vulnerability.
Fixed in 6.8.0-1054.57~22.04.1
Upgrade
Upgrade ubuntu/linux-hwe-6.8 to a version that resolves this vulnerability.
Fixed in 6.8.0-110.110~22.04.1
Upgrade
Upgrade ubuntu/linux-ibm-6.8 to a version that resolves this vulnerability.
Fixed in 6.8.0-1051.51~22.04.1
Upgrade
Upgrade ubuntu/linux-lowlatency-hwe-6.8 to a version that resolves this vulnerability.
Fixed in 6.8.0-110.110.1~22.04.1
Upgrade
Upgrade ubuntu/linux-nvidia-6.8 to a version that resolves this vulnerability.
Fixed in 6.8.0-1051.54~22.04.1
Upgrade
Upgrade ubuntu/linux-oracle-6.8 to a version that resolves this vulnerability.
Fixed in 6.8.0-1049.50~22.04.1
Upgrade
Upgrade ubuntu/linux-riscv-6.8 to a version that resolves this vulnerability.
Fixed in 6.8.0-110.110~22.04.1
Upgrade
Upgrade ubuntu/linux-realtime-6.8 to a version that resolves this vulnerability.
Fixed in 6.8.1-1047.48~22.04.1
Upgrade
Upgrade ubuntu/linux to a version that resolves this vulnerability.
Fixed in 6.8.0-110.110
Upgrade
Upgrade ubuntu/linux-aws to a version that resolves this vulnerability.
Fixed in 6.8.0-1052.55
Upgrade
Upgrade ubuntu/linux-aws-6.17 to a version that resolves this vulnerability.
Fixed in 6.17.0-1012.12~24.04.1
Upgrade
Upgrade ubuntu/linux-azure to a version that resolves this vulnerability.
Fixed in 6.8.0-1054.60
Upgrade
Upgrade ubuntu/linux-azure-6.17 to a version that resolves this vulnerability.
Fixed in 6.17.0-1013.13~24.04.1
Upgrade
Upgrade ubuntu/linux-azure-fde to a version that resolves this vulnerability.
Fixed in 6.8.0-1058.65
Upgrade
Upgrade ubuntu/linux-azure-nvidia to a version that resolves this vulnerability.
Fixed in 6.8.0-1039.42
Upgrade
Upgrade ubuntu/linux-gcp to a version that resolves this vulnerability.
Fixed in 6.8.0-1054.57
Upgrade
Upgrade ubuntu/linux-gcp-6.17 to a version that resolves this vulnerability.
Fixed in 6.17.0-1012.12~24.04.1
Upgrade
Upgrade ubuntu/linux-gke to a version that resolves this vulnerability.
Fixed in 6.8.0-1050.56
Upgrade
Upgrade ubuntu/linux-gkeop to a version that resolves this vulnerability.
Fixed in 6.8.0-1037.40
Upgrade
Upgrade ubuntu/linux-hwe-6.17 to a version that resolves this vulnerability.
Fixed in 6.17.0-22.22~24.04.1
Upgrade
Upgrade ubuntu/linux-ibm to a version that resolves this vulnerability.
Fixed in 6.8.0-1051.51
Upgrade
Upgrade ubuntu/linux-lowlatency to a version that resolves this vulnerability.
Fixed in 6.8.0-110.110.1
Upgrade
Upgrade ubuntu/linux-nvidia to a version that resolves this vulnerability.
Fixed in 6.8.0-1051.54
Upgrade
Upgrade ubuntu/linux-nvidia-6.17 to a version that resolves this vulnerability.
Fixed in 6.17.0-1018.18
Upgrade
Upgrade ubuntu/linux-nvidia-lowlatency to a version that resolves this vulnerability.
Fixed in 6.8.0-1051.54.1
Upgrade
Upgrade ubuntu/linux-nvidia-tegra to a version that resolves this vulnerability.
Fixed in 6.8.0-1022.22
Upgrade
Upgrade ubuntu/linux-oem-6.17 to a version that resolves this vulnerability.
Fixed in 6.17.0-1020.20
Upgrade
Upgrade ubuntu/linux-oracle to a version that resolves this vulnerability.
Fixed in 6.8.0-1049.50
Upgrade
Upgrade ubuntu/linux-oracle-6.17 to a version that resolves this vulnerability.
Fixed in 6.17.0-1011.11~24.04.1
Upgrade
Upgrade ubuntu/linux-raspi to a version that resolves this vulnerability.
Fixed in 6.8.0-1052.56
Upgrade
Upgrade ubuntu/linux-riscv-6.17 to a version that resolves this vulnerability.
Fixed in 6.17.0-22.22.1~24.04.1
Upgrade
Upgrade ubuntu/linux-xilinx to a version that resolves this vulnerability.
Fixed in 6.8.0-1028.29
Upgrade
Upgrade ubuntu/linux-bluefield to a version that resolves this vulnerability.
Fixed in 6.8.0-1017.21
Upgrade
Upgrade ubuntu/linux-raspi-realtime to a version that resolves this vulnerability.
Fixed in 6.8.0-2042.43
Upgrade
Upgrade ubuntu/linux-realtime to a version that resolves this vulnerability.
Fixed in 6.8.1-1047.48
Upgrade
Upgrade ubuntu/linux-realtime-6.17 to a version that resolves this vulnerability.
Fixed in 6.17.0-1010.11~24.04.1
Upgrade
Upgrade ubuntu/linux-aws-fips to a version that resolves this vulnerability.
Fixed in 6.8.0-1052.55+fips1
Upgrade
Upgrade ubuntu/linux-azure-fips to a version that resolves this vulnerability.
Fixed in 6.8.0-1053.59+fips1
Upgrade
Upgrade ubuntu/linux-fips to a version that resolves this vulnerability.
Fixed in 6.8.0-110.110+fips2
Upgrade
Upgrade ubuntu/linux-gcp-fips to a version that resolves this vulnerability.
Fixed in 6.8.0-1054.57+fips1
Upgrade
Upgrade ubuntu/linux to a version that resolves this vulnerability.
Fixed in 6.17.0-22.22
Upgrade
Upgrade ubuntu/linux-aws to a version that resolves this vulnerability.
Fixed in 6.17.0-1012.12
Upgrade
Upgrade ubuntu/linux-azure to a version that resolves this vulnerability.
Fixed in 6.17.0-1013.13
Upgrade
Upgrade ubuntu/linux-gcp to a version that resolves this vulnerability.
Fixed in 6.17.0-1012.12
Upgrade
Upgrade ubuntu/linux-oracle to a version that resolves this vulnerability.
Fixed in 6.17.0-1011.11
Upgrade
Upgrade ubuntu/linux-raspi to a version that resolves this vulnerability.
Fixed in 6.17.0-1013.13
Upgrade
Upgrade ubuntu/linux-realtime to a version that resolves this vulnerability.
Fixed in 6.17.0-1010.11
Upgrade
Upgrade ubuntu/linux-riscv to a version that resolves this vulnerability.
Fixed in 6.17.0-22.22.1

Event History

Jan 13, 2026

CVE Published

via OSV·04:16 PM

Data Sourced

via OSV·04:16 PM

DescriptionSeverityAffected Software

Frequently Asked Questions

Who is realistically exposed to this issue?

Systems using KVM with memslots initially created with a guest_memfd binding are exposed if a privileged local actor can modify those existing memslots. The listed affected Ubuntu kernel packages include linux-riscv, linux-realtime, linux-azure, linux-gcp, linux-azure-fde, linux-hwe-edge, linux-gke, and linux-gkeop.

What does an attacker need to do to trigger the flaw?

An attacker needs high privileges and local access, then must attempt to clear KVM_MEM_GUEST_MEMFD on an existing memslot that was created with a guest_memfd binding. KVM previously blocked enabling this flag on an existing memslot but did not block disabling it.

What is the impact of successful exploitation?

Clearing the flag can leave KVM bound to the guest_memfd instance and cause a use-after-free. The supplied severity vector indicates high impact to confidentiality, integrity, and availability of the vulnerable system.

How can I tell whether a system is using the affected configuration?

Review KVM users for memslots created with a guest_memfd binding and for later flags-only updates that clear KVM_MEM_GUEST_MEMFD. The vulnerability is specifically tied to toggling that flag off on an existing guest_memfd-backed memslot.

UBUNTU-CVE-2025-68810: Use After Free

Affected Software

Remediation

Event History

Frequently Asked Questions

Who is realistically exposed to this issue?

What does an attacker need to do to trigger the flaw?

What is the impact of successful exploitation?

How can I tell whether a system is using the affected configuration?

Company

Resources

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