UBUNTU-CVE-2025-21779: Medium severity ubuntu/linux-hwe-edge vulnerability

Q: Which systems are exposed to this issue?

Affected systems are Ubuntu hosts running the listed Linux kernel packages and using KVM x86 virtualization. Exposure requires a guest configuration that exposes Hyper-V enlightenments while the guest local APIC is emulated in userspace rather than in-kernel.

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

An attacker needs high privileges as indicated by the CVSS vector and must be able to invoke Hyper-V SEND_IPI or SEND_IPI_EX hypercalls from a relevant guest. The vulnerable condition can cause a NULL-pointer dereference in the host KVM code, resulting in a host availability impact.

Q: Is a default KVM configuration affected?

The provided information identifies the vulnerable condition specifically as Hyper-V enlightenments being exposed without an in-kernel local APIC. It does not state whether this combination is enabled by default.

Q: What is the mitigation if an updated kernel cannot be deployed immediately?

Avoid exposing Hyper-V SEND_IPI and SEND_IPI_EX hypercalls to guests that use userspace local APIC emulation. Using an in-kernel local APIC avoids the configuration described as vulnerable.

Q: How can administrators identify potentially affected virtual machines?

Review KVM guest configurations for Hyper-V enlightenments together with userspace local APIC emulation. A VM is potentially affected when Hyper-V SEND_IPI or SEND_IPI_EX support is exposed despite the local APIC not being in-kernel.

Published Feb 27, 2025

Updated

In the Linux kernel, the following vulnerability has been resolved: KVM: x86: Reject Hyper-V's SENDIPI hypercalls if local APIC isn't in-kernel Advertise support for Hyper-V's SENDIPI and SENDIPIEX hypercalls if and only if the local API is emulated/virtualized by KVM, and explicitly reject said hypercalls if the local APIC is emulated in userspace, i.e. don't rely on userspace to opt-in to KVMCAPHYPERVENFORCECPUID. Rejecting SENDIPI and SENDIPIEX fixes a NULL-pointer dereference if Hyper-V enlightenments are exposed to the guest without an in-kernel local APIC: dumpstack+0xbe/0xfd kasanreport.cold+0x34/0x84 kasanreport+0x3a/0x50 apicacceptirq+0x3a/0x5c0 kvmhvsendipi.isra.0+0x34e/0x820 kvmhvhypercall+0x8d9/0x9d0 kvmemulatehypercall+0x506/0x7e0 vmxhandleexit+0x283/0xb60 vmxhandleexit+0x1d/0xd0 vcpuenterguest+0x16b0/0x24c0 vcpurun+0xc0/0x550 kvmarchvcpuioctlrun+0x170/0x6d0 kvmvcpuioctl+0x413/0xb20 sesysioctl+0x111/0x160 dosyscal164+0x30/0x40 entrySYSCALL64afterhwframe+0x67/0xd1 Note, checking the sending vCPU is sufficient, as the per-VM irqchipmode can't be modified after vCPUs are created, i.e. if one vCPU has an in-kernel local APIC, then all vCPUs have an in-kernel local APIC.

Affected Software

181 affected componentsFixes available

ubuntu/linux-hwe-edge*

ubuntu/linux-aws-5.0*

ubuntu/linux-aws-5.3*

ubuntu/linux-aws-5.4*

ubuntu/linux-azure*

ubuntu/linux-azure-5.3*

ubuntu/linux-azure-5.4*

ubuntu/linux-azure-edge*

ubuntu/linux-gcp*

ubuntu/linux-gcp-5.3*

ubuntu/linux-gcp-5.4*

ubuntu/linux-gke-4.15*

ubuntu/linux-gke-5.4*

ubuntu/linux-gkeop-5.4*

ubuntu/linux-hwe*

ubuntu/linux-hwe-5.4*

ubuntu/linux-hwe-edge*

ubuntu/linux-ibm-5.4*

ubuntu/linux-oem*

ubuntu/linux-oracle-5.0*

ubuntu/linux-oracle-5.3*

ubuntu/linux-oracle-5.4*

ubuntu/linux-raspi-5.4*

ubuntu/linux-aws-5.15<5.15.0-1084.91~20.04.1

5.15.0-1084.91~20.04.1

ubuntu/linux-azure-5.15<5.15.0-1089.98~20.04.1

5.15.0-1089.98~20.04.1

ubuntu/linux-gcp-5.15<5.15.0-1083.92~20.04.1

5.15.0-1083.92~20.04.1

ubuntu/linux-ibm-5.15<5.15.0-1076.79~20.04.1

5.15.0-1076.79~20.04.1

ubuntu/linux-intel-iotg-5.15<5.15.0-1079.85~20.04.1

5.15.0-1079.85~20.04.1

ubuntu/linux-lowlatency-hwe-5.15<5.15.0-140.150~20.04.1

5.15.0-140.150~20.04.1

ubuntu/linux-oracle-5.15<5.15.0-1081.87~20.04.1

5.15.0-1081.87~20.04.1

ubuntu/linux-riscv-5.15<5.15.0-1079.83~20.04.1

5.15.0-1079.83~20.04.1

ubuntu/linux*

ubuntu/linux-aws*

ubuntu/linux-aws-5.11*

ubuntu/linux-aws-5.13*

ubuntu/linux-aws-5.8*

ubuntu/linux-azure*

ubuntu/linux-azure-5.11*

ubuntu/linux-azure-5.13*

ubuntu/linux-azure-5.8*

ubuntu/linux-azure-fde*

ubuntu/linux-bluefield*

ubuntu/linux-gcp*

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-5.15<5.15.0-142.152~20.04.1

5.15.0-142.152~20.04.1

ubuntu/linux-hwe-5.8*

ubuntu/linux-ibm*

ubuntu/linux-intel-5.13*

ubuntu/linux-iot*

ubuntu/linux-kvm*

ubuntu/linux-nvidia-tegra-5.15<5.15.0-1039.39~20.04.1

5.15.0-1039.39~20.04.1

ubuntu/linux-oem-5.10*

ubuntu/linux-oem-5.13*

ubuntu/linux-oem-5.6*

ubuntu/linux-oracle*

ubuntu/linux-oracle-5.11*

ubuntu/linux-oracle-5.13*

ubuntu/linux-oracle-5.8*

ubuntu/linux-raspi*

ubuntu/linux-raspi2*

ubuntu/linux-riscv*

ubuntu/linux-riscv-5.11*

ubuntu/linux-riscv-5.8*

ubuntu/linux-xilinx-zynqmp*

ubuntu/linux-aws-fips*

ubuntu/linux-azure-fips*

ubuntu/linux-fips*

ubuntu/linux-gcp-fips*

ubuntu/linux-aws-fips*

ubuntu/linux-azure-fips*

ubuntu/linux-fips*

ubuntu/linux-gcp-fips*

ubuntu/linux<5.15.0-140.150

5.15.0-140.150

ubuntu/linux-allwinner-5.19*

ubuntu/linux-aws<5.15.0-1084.91

5.15.0-1084.91

ubuntu/linux-aws-5.19*

ubuntu/linux-aws-6.2*

ubuntu/linux-aws-6.5*

ubuntu/linux-aws-6.8<6.8.0-1035.37~22.04.1

6.8.0-1035.37~22.04.1

ubuntu/linux-azure<5.15.0-1089.98

5.15.0-1089.98

ubuntu/linux-azure-5.19*

ubuntu/linux-azure-6.2*

ubuntu/linux-azure-6.5*

ubuntu/linux-azure-6.8<6.8.0-1034.39~22.04.1

6.8.0-1034.39~22.04.1

ubuntu/linux-azure-fde<5.15.0-1089.98.1

5.15.0-1089.98.1

ubuntu/linux-azure-fde-5.19*

ubuntu/linux-azure-fde-6.2*

ubuntu/linux-gcp<5.15.0-1083.92

5.15.0-1083.92

ubuntu/linux-gcp-5.19*

ubuntu/linux-gcp-6.2*

ubuntu/linux-gcp-6.5*

ubuntu/linux-gcp-6.8<6.8.0-1036.38~22.04.1

6.8.0-1036.38~22.04.1

ubuntu/linux-gke<5.15.0-1081.87

5.15.0-1081.87

ubuntu/linux-gkeop<5.15.0-1066.74

5.15.0-1066.74

ubuntu/linux-hwe-5.19*

ubuntu/linux-hwe-6.2*

ubuntu/linux-hwe-6.5*

ubuntu/linux-hwe-6.8<6.8.0-78.78~22.04.1

6.8.0-78.78~22.04.1

ubuntu/linux-ibm<5.15.0-1076.79

5.15.0-1076.79

ubuntu/linux-ibm-6.8<6.8.0-1033.33~22.04.1

6.8.0-1033.33~22.04.1

ubuntu/linux-intel-iot-realtime*

ubuntu/linux-intel-iotg<5.15.0-1079.85

5.15.0-1079.85

ubuntu/linux-kvm<5.15.0-1080.85

5.15.0-1080.85

ubuntu/linux-lowlatency<5.15.0-140.150

5.15.0-140.150

ubuntu/linux-lowlatency-hwe-5.19*

ubuntu/linux-lowlatency-hwe-6.2*

ubuntu/linux-lowlatency-hwe-6.5*

ubuntu/linux-lowlatency-hwe-6.8<6.8.0-78.78.1~22.04.1

6.8.0-78.78.1~22.04.1

ubuntu/linux-nvidia<5.15.0-1078.79

5.15.0-1078.79

ubuntu/linux-nvidia-6.2*

ubuntu/linux-nvidia-6.5*

ubuntu/linux-nvidia-6.8<6.8.0-1035.38~22.04.1

6.8.0-1035.38~22.04.1

ubuntu/linux-nvidia-tegra<5.15.0-1037.37

5.15.0-1037.37

ubuntu/linux-nvidia-tegra-igx<5.15.0-1026.26

5.15.0-1026.26

ubuntu/linux-oem-5.17*

ubuntu/linux-oem-6.0*

ubuntu/linux-oem-6.1*

ubuntu/linux-oem-6.5*

ubuntu/linux-oracle<5.15.0-1081.87

5.15.0-1081.87

ubuntu/linux-oracle-6.5*

ubuntu/linux-oracle-6.8<6.8.0-1032.33~22.04.1

6.8.0-1032.33~22.04.1

ubuntu/linux-raspi<5.15.0-1078.81

5.15.0-1078.81

ubuntu/linux-realtime*

ubuntu/linux-riscv*

ubuntu/linux-riscv-5.19*

ubuntu/linux-riscv-6.5*

ubuntu/linux-riscv-6.8<6.8.0-78.78~22.04.1

6.8.0-78.78~22.04.1

ubuntu/linux-starfive-5.19*

ubuntu/linux-starfive-6.2*

ubuntu/linux-starfive-6.5*

ubuntu/linux-xilinx-zynqmp<5.15.0-1050.54

5.15.0-1050.54

ubuntu/linux-bluefield<5.15.0-1066.68

5.15.0-1066.68

ubuntu/linux-intel-iot-realtime<5.15.0-1077.79

5.15.0-1077.79

ubuntu/linux-realtime<5.15.0-1084.93

5.15.0-1084.93

ubuntu/linux-realtime-6.8<6.8.1-1030.31~22.04.1

6.8.1-1030.31~22.04.1

ubuntu/linux-aws-fips*

ubuntu/linux-azure-fips*

ubuntu/linux-fips*

ubuntu/linux-gcp-fips*

ubuntu/linux-aws-fips<5.15.0-1084.91+fips1

5.15.0-1084.91+fips1

ubuntu/linux-azure-fips<5.15.0-1089.98+fips1

5.15.0-1089.98+fips1

ubuntu/linux-fips<5.15.0-140.150+fips1

5.15.0-140.150+fips1

ubuntu/linux-gcp-fips<5.15.0-1083.92+fips1

5.15.0-1083.92+fips1

ubuntu/linux<6.8.0-78.78

6.8.0-78.78

ubuntu/linux-aws<6.8.0-1035.37

6.8.0-1035.37

ubuntu/linux-azure<6.8.0-1034.39

6.8.0-1034.39

ubuntu/linux-azure-6.11<6.11.0-1015.15~24.04.1

6.11.0-1015.15~24.04.1

ubuntu/linux-azure-nvidia<6.8.0-1022.23

6.8.0-1022.23

ubuntu/linux-gcp<6.8.0-1036.38

6.8.0-1036.38

ubuntu/linux-gcp-6.11<6.11.0-1015.15~24.04.1

6.11.0-1015.15~24.04.1

ubuntu/linux-gke<6.8.0-1032.36

6.8.0-1032.36

ubuntu/linux-gkeop<6.8.0-1019.21

6.8.0-1019.21

ubuntu/linux-hwe-6.11<6.11.0-26.26~24.04.1

6.11.0-26.26~24.04.1

ubuntu/linux-ibm<6.8.0-1033.33

6.8.0-1033.33

ubuntu/linux-intel*

ubuntu/linux-lowlatency<6.8.0-78.78.1

6.8.0-78.78.1

ubuntu/linux-lowlatency-hwe-6.11<6.11.0-1014.15~24.04.1

6.11.0-1014.15~24.04.1

ubuntu/linux-nvidia<6.8.0-1035.38

6.8.0-1035.38

ubuntu/linux-nvidia-6.11<6.11.0-1010.10

6.11.0-1010.10

ubuntu/linux-nvidia-lowlatency<6.8.0-1035.38.1

6.8.0-1035.38.1

ubuntu/linux-nvidia-tegra<6.8.0-1009.9

6.8.0-1009.9

ubuntu/linux-oem-6.11<6.11.0-1022.22

6.11.0-1022.22

ubuntu/linux-oem-6.8*

ubuntu/linux-oracle<6.8.0-1032.33

6.8.0-1032.33

ubuntu/linux-raspi<6.8.0-1035.39

6.8.0-1035.39

ubuntu/linux-raspi-realtime*

ubuntu/linux-realtime*

ubuntu/linux-riscv*

ubuntu/linux-xilinx<6.8.0-1017.18

6.8.0-1017.18

ubuntu/linux-raspi-realtime<6.8.0-2028.29

6.8.0-2028.29

ubuntu/linux-realtime<6.8.1-1030.31

6.8.1-1030.31

ubuntu/linux-fips<6.8.0-78.78+fips1

6.8.0-78.78+fips1

ubuntu/linux-vmware*

Remediation

Recommended actions to resolve this vulnerability, in priority order.

Upgrade
Upgrade ubuntu/linux-aws-5.15 to a version that resolves this vulnerability.
Fixed in 5.15.0-1084.91~20.04.1
Upgrade
Upgrade ubuntu/linux-azure-5.15 to a version that resolves this vulnerability.
Fixed in 5.15.0-1089.98~20.04.1
Upgrade
Upgrade ubuntu/linux-gcp-5.15 to a version that resolves this vulnerability.
Fixed in 5.15.0-1083.92~20.04.1
Upgrade
Upgrade ubuntu/linux-ibm-5.15 to a version that resolves this vulnerability.
Fixed in 5.15.0-1076.79~20.04.1
Upgrade
Upgrade ubuntu/linux-intel-iotg-5.15 to a version that resolves this vulnerability.
Fixed in 5.15.0-1079.85~20.04.1
Upgrade
Upgrade ubuntu/linux-lowlatency-hwe-5.15 to a version that resolves this vulnerability.
Fixed in 5.15.0-140.150~20.04.1
Upgrade
Upgrade ubuntu/linux-oracle-5.15 to a version that resolves this vulnerability.
Fixed in 5.15.0-1081.87~20.04.1
Upgrade
Upgrade ubuntu/linux-riscv-5.15 to a version that resolves this vulnerability.
Fixed in 5.15.0-1079.83~20.04.1
Upgrade
Upgrade ubuntu/linux-hwe-5.15 to a version that resolves this vulnerability.
Fixed in 5.15.0-142.152~20.04.1
Upgrade
Upgrade ubuntu/linux-nvidia-tegra-5.15 to a version that resolves this vulnerability.
Fixed in 5.15.0-1039.39~20.04.1
Upgrade
Upgrade ubuntu/linux to a version that resolves this vulnerability.
Fixed in 5.15.0-140.150
Upgrade
Upgrade ubuntu/linux-aws to a version that resolves this vulnerability.
Fixed in 5.15.0-1084.91
Upgrade
Upgrade ubuntu/linux-aws-6.8 to a version that resolves this vulnerability.
Fixed in 6.8.0-1035.37~22.04.1
Upgrade
Upgrade ubuntu/linux-azure to a version that resolves this vulnerability.
Fixed in 5.15.0-1089.98
Upgrade
Upgrade ubuntu/linux-azure-6.8 to a version that resolves this vulnerability.
Fixed in 6.8.0-1034.39~22.04.1
Upgrade
Upgrade ubuntu/linux-azure-fde to a version that resolves this vulnerability.
Fixed in 5.15.0-1089.98.1
Upgrade
Upgrade ubuntu/linux-gcp to a version that resolves this vulnerability.
Fixed in 5.15.0-1083.92
Upgrade
Upgrade ubuntu/linux-gcp-6.8 to a version that resolves this vulnerability.
Fixed in 6.8.0-1036.38~22.04.1
Upgrade
Upgrade ubuntu/linux-gke to a version that resolves this vulnerability.
Fixed in 5.15.0-1081.87
Upgrade
Upgrade ubuntu/linux-gkeop to a version that resolves this vulnerability.
Fixed in 5.15.0-1066.74
Upgrade
Upgrade ubuntu/linux-hwe-6.8 to a version that resolves this vulnerability.
Fixed in 6.8.0-78.78~22.04.1
Upgrade
Upgrade ubuntu/linux-ibm to a version that resolves this vulnerability.
Fixed in 5.15.0-1076.79
Upgrade
Upgrade ubuntu/linux-ibm-6.8 to a version that resolves this vulnerability.
Fixed in 6.8.0-1033.33~22.04.1
Upgrade
Upgrade ubuntu/linux-intel-iotg to a version that resolves this vulnerability.
Fixed in 5.15.0-1079.85
Upgrade
Upgrade ubuntu/linux-kvm to a version that resolves this vulnerability.
Fixed in 5.15.0-1080.85
Upgrade
Upgrade ubuntu/linux-lowlatency to a version that resolves this vulnerability.
Fixed in 5.15.0-140.150
Upgrade
Upgrade ubuntu/linux-lowlatency-hwe-6.8 to a version that resolves this vulnerability.
Fixed in 6.8.0-78.78.1~22.04.1
Upgrade
Upgrade ubuntu/linux-nvidia to a version that resolves this vulnerability.
Fixed in 5.15.0-1078.79
Upgrade
Upgrade ubuntu/linux-nvidia-6.8 to a version that resolves this vulnerability.
Fixed in 6.8.0-1035.38~22.04.1
Upgrade
Upgrade ubuntu/linux-nvidia-tegra to a version that resolves this vulnerability.
Fixed in 5.15.0-1037.37
Upgrade
Upgrade ubuntu/linux-nvidia-tegra-igx to a version that resolves this vulnerability.
Fixed in 5.15.0-1026.26
Upgrade
Upgrade ubuntu/linux-oracle to a version that resolves this vulnerability.
Fixed in 5.15.0-1081.87
Upgrade
Upgrade ubuntu/linux-oracle-6.8 to a version that resolves this vulnerability.
Fixed in 6.8.0-1032.33~22.04.1
Upgrade
Upgrade ubuntu/linux-raspi to a version that resolves this vulnerability.
Fixed in 5.15.0-1078.81
Upgrade
Upgrade ubuntu/linux-riscv-6.8 to a version that resolves this vulnerability.
Fixed in 6.8.0-78.78~22.04.1
Upgrade
Upgrade ubuntu/linux-xilinx-zynqmp to a version that resolves this vulnerability.
Fixed in 5.15.0-1050.54
Upgrade
Upgrade ubuntu/linux-bluefield to a version that resolves this vulnerability.
Fixed in 5.15.0-1066.68
Upgrade
Upgrade ubuntu/linux-intel-iot-realtime to a version that resolves this vulnerability.
Fixed in 5.15.0-1077.79
Upgrade
Upgrade ubuntu/linux-realtime to a version that resolves this vulnerability.
Fixed in 5.15.0-1084.93
Upgrade
Upgrade ubuntu/linux-realtime-6.8 to a version that resolves this vulnerability.
Fixed in 6.8.1-1030.31~22.04.1
Upgrade
Upgrade ubuntu/linux-aws-fips to a version that resolves this vulnerability.
Fixed in 5.15.0-1084.91+fips1
Upgrade
Upgrade ubuntu/linux-azure-fips to a version that resolves this vulnerability.
Fixed in 5.15.0-1089.98+fips1
Upgrade
Upgrade ubuntu/linux-fips to a version that resolves this vulnerability.
Fixed in 5.15.0-140.150+fips1
Upgrade
Upgrade ubuntu/linux-gcp-fips to a version that resolves this vulnerability.
Fixed in 5.15.0-1083.92+fips1
Upgrade
Upgrade ubuntu/linux to a version that resolves this vulnerability.
Fixed in 6.8.0-78.78
Upgrade
Upgrade ubuntu/linux-aws to a version that resolves this vulnerability.
Fixed in 6.8.0-1035.37
Upgrade
Upgrade ubuntu/linux-azure to a version that resolves this vulnerability.
Fixed in 6.8.0-1034.39
Upgrade
Upgrade ubuntu/linux-azure-6.11 to a version that resolves this vulnerability.
Fixed in 6.11.0-1015.15~24.04.1
Upgrade
Upgrade ubuntu/linux-azure-nvidia to a version that resolves this vulnerability.
Fixed in 6.8.0-1022.23
Upgrade
Upgrade ubuntu/linux-gcp to a version that resolves this vulnerability.
Fixed in 6.8.0-1036.38
Upgrade
Upgrade ubuntu/linux-gcp-6.11 to a version that resolves this vulnerability.
Fixed in 6.11.0-1015.15~24.04.1
Upgrade
Upgrade ubuntu/linux-gke to a version that resolves this vulnerability.
Fixed in 6.8.0-1032.36
Upgrade
Upgrade ubuntu/linux-gkeop to a version that resolves this vulnerability.
Fixed in 6.8.0-1019.21
Upgrade
Upgrade ubuntu/linux-hwe-6.11 to a version that resolves this vulnerability.
Fixed in 6.11.0-26.26~24.04.1
Upgrade
Upgrade ubuntu/linux-ibm to a version that resolves this vulnerability.
Fixed in 6.8.0-1033.33
Upgrade
Upgrade ubuntu/linux-lowlatency to a version that resolves this vulnerability.
Fixed in 6.8.0-78.78.1
Upgrade
Upgrade ubuntu/linux-lowlatency-hwe-6.11 to a version that resolves this vulnerability.
Fixed in 6.11.0-1014.15~24.04.1
Upgrade
Upgrade ubuntu/linux-nvidia to a version that resolves this vulnerability.
Fixed in 6.8.0-1035.38
Upgrade
Upgrade ubuntu/linux-nvidia-6.11 to a version that resolves this vulnerability.
Fixed in 6.11.0-1010.10
Upgrade
Upgrade ubuntu/linux-nvidia-lowlatency to a version that resolves this vulnerability.
Fixed in 6.8.0-1035.38.1
Upgrade
Upgrade ubuntu/linux-nvidia-tegra to a version that resolves this vulnerability.
Fixed in 6.8.0-1009.9
Upgrade
Upgrade ubuntu/linux-oem-6.11 to a version that resolves this vulnerability.
Fixed in 6.11.0-1022.22
Upgrade
Upgrade ubuntu/linux-oracle to a version that resolves this vulnerability.
Fixed in 6.8.0-1032.33
Upgrade
Upgrade ubuntu/linux-raspi to a version that resolves this vulnerability.
Fixed in 6.8.0-1035.39
Upgrade
Upgrade ubuntu/linux-xilinx to a version that resolves this vulnerability.
Fixed in 6.8.0-1017.18
Upgrade
Upgrade ubuntu/linux-raspi-realtime to a version that resolves this vulnerability.
Fixed in 6.8.0-2028.29
Upgrade
Upgrade ubuntu/linux-realtime to a version that resolves this vulnerability.
Fixed in 6.8.1-1030.31
Upgrade
Upgrade ubuntu/linux-fips to a version that resolves this vulnerability.
Fixed in 6.8.0-78.78+fips1

Event History

Feb 27, 2025

CVE Published

via OSV·03:15 AM

Data Sourced

via OSV·03:15 AM

DescriptionSeverityAffected Software

Frequently Asked Questions

Which systems are exposed to this issue?

Affected systems are Ubuntu hosts running the listed Linux kernel packages and using KVM x86 virtualization. Exposure requires a guest configuration that exposes Hyper-V enlightenments while the guest local APIC is emulated in userspace rather than in-kernel.

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

An attacker needs high privileges as indicated by the CVSS vector and must be able to invoke Hyper-V SEND_IPI or SEND_IPI_EX hypercalls from a relevant guest. The vulnerable condition can cause a NULL-pointer dereference in the host KVM code, resulting in a host availability impact.

Is a default KVM configuration affected?

The provided information identifies the vulnerable condition specifically as Hyper-V enlightenments being exposed without an in-kernel local APIC. It does not state whether this combination is enabled by default.

What is the mitigation if an updated kernel cannot be deployed immediately?

Avoid exposing Hyper-V SEND_IPI and SEND_IPI_EX hypercalls to guests that use userspace local APIC emulation. Using an in-kernel local APIC avoids the configuration described as vulnerable.

How can administrators identify potentially affected virtual machines?

Review KVM guest configurations for Hyper-V enlightenments together with userspace local APIC emulation. A VM is potentially affected when Hyper-V SEND_IPI or SEND_IPI_EX support is exposed despite the local APIC not being in-kernel.

UBUNTU-CVE-2025-21779: Medium severity ubuntu/linux-hwe-edge vulnerability

Affected Software

Remediation

Event History

Frequently Asked Questions

Which systems are exposed to this issue?

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

Is a default KVM configuration affected?

What is the mitigation if an updated kernel cannot be deployed immediately?

How can administrators identify potentially affected virtual machines?

Company

Resources

Contact

Frequently Asked Questions

Which systems are exposed to this issue?

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

Is a default KVM configuration affected?

What is the mitigation if an updated kernel cannot be deployed immediately?

How can administrators identify potentially affected virtual machines?