UBUNTU-CVE-2025-21920: Medium severity ubuntu/linux vulnerability

Q: What access does an attacker need to exploit this issue?

The issue requires local access and low privileges. The described reproduction creates and configures network tunnel and VLAN interfaces, and no user interaction is required.

Q: Which systems are realistically exposed?

Systems are exposed if a local low-privileged user can create a VLAN interface over a non-Ethernet device whose address length exceeds six bytes. The example uses an IPv6 GRE tunnel as the VLAN's underlying device.

Q: Are normal VLAN configurations affected?

The vulnerable behavior occurs when VLAN devices are allowed on non-Ethernet underlying devices. The fix enforces the underlying device type during VLAN initialization, so ordinary VLANs over Ethernet are not the configuration described as triggering the out-of-bounds read.

Q: How can I check for signs of exploitation or exposure?

The provided reproduction checks multicast addresses with "ip maddr show" and looks for "01:80:c2:00:00:21", which can reveal the address of the kernel function garp_pdu_rcv. Review whether users can create VLAN devices on GRE or other non-Ethernet interfaces.

Published Apr 1, 2025

Updated

In the Linux kernel, the following vulnerability has been resolved: vlan: enforce underlying device type Currently, VLAN devices can be created on top of non-ethernet devices. Besides the fact that it doesn't make much sense, this also causes a bug which leaks the address of a kernel function to usermode. When creating a VLAN device, we initialize GARP (garpinitapplicant) and MRP (mrpinitapplicant) for the underlying device. As part of the initialization process, we add the multicast address of each applicant to the underlying device, by calling devmcadd. devmcadd uses dev->addrlen to determine the length of the new multicast address. This causes an out-of-bounds read if dev->addrlen is greater than 6, since the multicast addresses provided by GARP and MRP are only 6 bytes long. This behaviour can be reproduced using the following commands: ip tunnel add gretest mode ip6gre local ::1 remote ::2 dev lo ip l set up dev gretest ip link add link gretest name vlantest type vlan id 100 Then, the following command will display the address of garppdurcv: ip maddr show | grep 01:80:c2:00:00:21 Fix the bug by enforcing the type of the underlying device during VLAN device initialization.

Affected Software

212 affected componentsFixes available

ubuntu/linux*

ubuntu/linux-aws*

ubuntu/linux-azure*

ubuntu/linux-lts-xenial*

ubuntu/linux*

ubuntu/linux-aws*

ubuntu/linux-aws-hwe*

ubuntu/linux-azure*

ubuntu/linux-gcp*

ubuntu/linux-hwe*

ubuntu/linux-hwe-edge*

ubuntu/linux-kvm*

ubuntu/linux-oracle*

ubuntu/linux-fips*

ubuntu/linux*

ubuntu/linux-aws*

ubuntu/linux-aws-5.0*

ubuntu/linux-aws-5.3*

ubuntu/linux-aws-5.4<5.4.0-1146.156~18.04.1

5.4.0-1146.156~18.04.1

ubuntu/linux-azure*

ubuntu/linux-azure-4.15*

ubuntu/linux-azure-5.3*

ubuntu/linux-azure-5.4<5.4.0-1151.158~18.04.1

5.4.0-1151.158~18.04.1

ubuntu/linux-azure-edge*

ubuntu/linux-gcp*

ubuntu/linux-gcp-4.15*

ubuntu/linux-gcp-5.3*

ubuntu/linux-gcp-5.4<5.4.0-1149.158~18.04.1

5.4.0-1149.158~18.04.1

ubuntu/linux-gke-4.15*

ubuntu/linux-gke-5.4*

ubuntu/linux-gkeop-5.4*

ubuntu/linux-hwe*

ubuntu/linux-hwe-5.4<5.4.0-216.236~18.04.1

5.4.0-216.236~18.04.1

ubuntu/linux-hwe-edge*

ubuntu/linux-ibm-5.4<5.4.0-1092.97~18.04.1

5.4.0-1092.97~18.04.1

ubuntu/linux-kvm*

ubuntu/linux-oem*

ubuntu/linux-oracle*

ubuntu/linux-oracle-5.0*

ubuntu/linux-oracle-5.3*

ubuntu/linux-oracle-5.4<5.4.0-1144.154~18.04.1

5.4.0-1144.154~18.04.1

ubuntu/linux-raspi-5.4<5.4.0-1129.142~18.04.1

5.4.0-1129.142~18.04.1

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<5.4.0-216.236

5.4.0-216.236

ubuntu/linux-aws<5.4.0-1146.156

5.4.0-1146.156

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

5.15.0-1084.91~20.04.1

ubuntu/linux-azure<5.4.0-1151.158

5.4.0-1151.158

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

5.15.0-1089.98~20.04.1

ubuntu/linux-bluefield<5.4.0-1105.112

5.4.0-1105.112

ubuntu/linux-gcp<5.4.0-1149.158

5.4.0-1149.158

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

5.15.0-1083.92~20.04.1

ubuntu/linux-ibm<5.4.0-1092.97

5.4.0-1092.97

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-kvm<5.4.0-1133.142

5.4.0-1133.142

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<5.4.0-1144.154

5.4.0-1144.154

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

5.15.0-1081.87~20.04.1

ubuntu/linux-raspi<5.4.0-1129.142

5.4.0-1129.142

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

5.15.0-1079.83~20.04.1

ubuntu/linux-xilinx-zynqmp<5.4.0-1064.68

5.4.0-1064.68

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-5.15<5.15.0-142.152~20.04.1

5.15.0-142.152~20.04.1

ubuntu/linux-hwe-5.8*

ubuntu/linux-intel-5.13*

ubuntu/linux-iot<5.4.0-1051.54

5.4.0-1051.54

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-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-aws-fips<5.4.0-1146.156+fips1

5.4.0-1146.156+fips1

ubuntu/linux-azure-fips<5.4.0-1151.158+fips1

5.4.0-1151.158+fips1

ubuntu/linux-fips<5.4.0-1120.130

5.4.0-1120.130

ubuntu/linux-gcp-fips<5.4.0-1149.158+fips1

5.4.0-1149.158+fips1

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<6.8.0-1039.41~22.04.1

6.8.0-1039.41~22.04.1

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<6.8.0-1036.42~22.04.1

6.8.0-1036.42~22.04.1

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<6.8.0-1040.42~22.04.1

6.8.0-1040.42~22.04.1

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<6.8.0-85.85~22.04.1

6.8.0-85.85~22.04.1

ubuntu/linux-ibm<5.15.0-1076.79

5.15.0-1076.79

ubuntu/linux-ibm-6.8<6.8.0-1037.37~22.04.1

6.8.0-1037.37~22.04.1

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<6.8.0-84.84.1~22.04.1

6.8.0-84.84.1~22.04.1

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<6.8.0-1039.42~22.04.1

6.8.0-1039.42~22.04.1

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<6.8.0-1037.38~22.04.1

6.8.0-1037.38~22.04.1

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<6.8.0-84.84~22.04.1

6.8.0-84.84~22.04.1

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<6.8.1-1034.35~22.04.1

6.8.1-1034.35~22.04.1

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<6.8.0-84.84

6.8.0-84.84

ubuntu/linux-aws<6.8.0-1039.41

6.8.0-1039.41

ubuntu/linux-azure<6.8.0-1038.44

6.8.0-1038.44

ubuntu/linux-azure-6.11<6.11.0-1018.18~24.04.1

6.11.0-1018.18~24.04.1

ubuntu/linux-azure-nvidia<6.8.0-1025.27

6.8.0-1025.27

ubuntu/linux-gcp<6.8.0-1040.42

6.8.0-1040.42

ubuntu/linux-gcp-6.11<6.11.0-1016.16~24.04.1

6.11.0-1016.16~24.04.1

ubuntu/linux-gke<6.8.0-1036.40

6.8.0-1036.40

ubuntu/linux-gkeop<6.8.0-1023.25

6.8.0-1023.25

ubuntu/linux-hwe-6.11<6.11.0-28.28~24.04.1

6.11.0-28.28~24.04.1

ubuntu/linux-ibm<6.8.0-1037.37

6.8.0-1037.37

ubuntu/linux-intel*

ubuntu/linux-lowlatency<6.8.0-84.84.1

6.8.0-84.84.1

ubuntu/linux-lowlatency-hwe-6.11<6.11.0-1015.16~24.04.2

6.11.0-1015.16~24.04.2

ubuntu/linux-nvidia<6.8.0-1039.42

6.8.0-1039.42

ubuntu/linux-nvidia-6.11<6.11.0-1012.12

6.11.0-1012.12

ubuntu/linux-nvidia-lowlatency<6.8.0-1039.42.1

6.8.0-1039.42.1

ubuntu/linux-nvidia-tegra<6.8.0-1010.10

6.8.0-1010.10

ubuntu/linux-oem-6.11<6.11.0-1024.24

6.11.0-1024.24

ubuntu/linux-oem-6.8*

ubuntu/linux-oracle<6.8.0-1037.38

6.8.0-1037.38

ubuntu/linux-raspi<6.8.0-1039.43

6.8.0-1039.43

ubuntu/linux-raspi-realtime*

ubuntu/linux-realtime*

ubuntu/linux-riscv*

ubuntu/linux-xilinx<6.8.0-1018.19

6.8.0-1018.19

ubuntu/linux-raspi-realtime<6.8.0-2030.31

6.8.0-2030.31

ubuntu/linux-realtime<6.8.1-1034.35

6.8.1-1034.35

ubuntu/linux-aws-fips<6.8.0-1039.41+fips1

6.8.0-1039.41+fips1

ubuntu/linux-azure-fips<6.8.0-1040.46+fips1

6.8.0-1040.46+fips1

ubuntu/linux-fips<6.8.0-84.84+fips1

6.8.0-84.84+fips1

ubuntu/linux-gcp-fips<6.8.0-1040.42+fips1

6.8.0-1040.42+fips1

ubuntu/linux-vmware*

Remediation

Recommended actions to resolve this vulnerability, in priority order.

Upgrade
Upgrade ubuntu/linux-aws-5.4 to a version that resolves this vulnerability.
Fixed in 5.4.0-1146.156~18.04.1
Upgrade
Upgrade ubuntu/linux-azure-5.4 to a version that resolves this vulnerability.
Fixed in 5.4.0-1151.158~18.04.1
Upgrade
Upgrade ubuntu/linux-gcp-5.4 to a version that resolves this vulnerability.
Fixed in 5.4.0-1149.158~18.04.1
Upgrade
Upgrade ubuntu/linux-hwe-5.4 to a version that resolves this vulnerability.
Fixed in 5.4.0-216.236~18.04.1
Upgrade
Upgrade ubuntu/linux-ibm-5.4 to a version that resolves this vulnerability.
Fixed in 5.4.0-1092.97~18.04.1
Upgrade
Upgrade ubuntu/linux-oracle-5.4 to a version that resolves this vulnerability.
Fixed in 5.4.0-1144.154~18.04.1
Upgrade
Upgrade ubuntu/linux-raspi-5.4 to a version that resolves this vulnerability.
Fixed in 5.4.0-1129.142~18.04.1
Upgrade
Upgrade ubuntu/linux to a version that resolves this vulnerability.
Fixed in 5.4.0-216.236
Upgrade
Upgrade ubuntu/linux-aws to a version that resolves this vulnerability.
Fixed in 5.4.0-1146.156
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 to a version that resolves this vulnerability.
Fixed in 5.4.0-1151.158
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-bluefield to a version that resolves this vulnerability.
Fixed in 5.4.0-1105.112
Upgrade
Upgrade ubuntu/linux-gcp to a version that resolves this vulnerability.
Fixed in 5.4.0-1149.158
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 to a version that resolves this vulnerability.
Fixed in 5.4.0-1092.97
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-kvm to a version that resolves this vulnerability.
Fixed in 5.4.0-1133.142
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 to a version that resolves this vulnerability.
Fixed in 5.4.0-1144.154
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-raspi to a version that resolves this vulnerability.
Fixed in 5.4.0-1129.142
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-xilinx-zynqmp to a version that resolves this vulnerability.
Fixed in 5.4.0-1064.68
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-iot to a version that resolves this vulnerability.
Fixed in 5.4.0-1051.54
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-aws-fips to a version that resolves this vulnerability.
Fixed in 5.4.0-1146.156+fips1
Upgrade
Upgrade ubuntu/linux-azure-fips to a version that resolves this vulnerability.
Fixed in 5.4.0-1151.158+fips1
Upgrade
Upgrade ubuntu/linux-fips to a version that resolves this vulnerability.
Fixed in 5.4.0-1120.130
Upgrade
Upgrade ubuntu/linux-gcp-fips to a version that resolves this vulnerability.
Fixed in 5.4.0-1149.158+fips1
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 6.8.0-1039.41~22.04.1
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 6.8.0-1036.42~22.04.1
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 6.8.0-1040.42~22.04.1
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 6.8.0-85.85~22.04.1
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 6.8.0-1037.37~22.04.1
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 6.8.0-84.84.1~22.04.1
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 6.8.0-1039.42~22.04.1
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 6.8.0-1037.38~22.04.1
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 6.8.0-84.84~22.04.1
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 6.8.1-1034.35~22.04.1
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
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Fixed in 5.15.0-140.150+fips1
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Fixed in 5.15.0-1083.92+fips1
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Fixed in 6.8.0-84.84
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Fixed in 6.8.0-1039.41
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Fixed in 6.8.0-1038.44
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Fixed in 6.11.0-1018.18~24.04.1
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Fixed in 6.8.0-1025.27
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Fixed in 6.8.0-1040.42
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Fixed in 6.11.0-1016.16~24.04.1
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Fixed in 6.8.0-1036.40
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Fixed in 6.8.0-1023.25
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Fixed in 6.11.0-28.28~24.04.1
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Fixed in 6.8.0-1037.37
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Fixed in 6.8.0-84.84.1
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Fixed in 6.11.0-1015.16~24.04.2
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Fixed in 6.8.0-1039.42
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Fixed in 6.11.0-1012.12
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Fixed in 6.8.0-1039.42.1
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Fixed in 6.8.0-1010.10
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Fixed in 6.11.0-1024.24
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Fixed in 6.8.0-1037.38
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Fixed in 6.8.0-1039.43
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Fixed in 6.8.0-1018.19
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Fixed in 6.8.0-2030.31
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Fixed in 6.8.1-1034.35
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Fixed in 6.8.0-1039.41+fips1
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Fixed in 6.8.0-1040.46+fips1
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Fixed in 6.8.0-84.84+fips1
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Fixed in 6.8.0-1040.42+fips1

Event History

Apr 1, 2025

CVE Published

via OSV·04:15 PM

Data Sourced

via OSV·04:15 PM

DescriptionSeverityAffected Software

Frequently Asked Questions

What access does an attacker need to exploit this issue?

The issue requires local access and low privileges. The described reproduction creates and configures network tunnel and VLAN interfaces, and no user interaction is required.

Which systems are realistically exposed?

Systems are exposed if a local low-privileged user can create a VLAN interface over a non-Ethernet device whose address length exceeds six bytes. The example uses an IPv6 GRE tunnel as the VLAN's underlying device.

Are normal VLAN configurations affected?

The vulnerable behavior occurs when VLAN devices are allowed on non-Ethernet underlying devices. The fix enforces the underlying device type during VLAN initialization, so ordinary VLANs over Ethernet are not the configuration described as triggering the out-of-bounds read.

How can I check for signs of exploitation or exposure?

The provided reproduction checks multicast addresses with "ip maddr show" and looks for "01:80:c2:00:00:21", which can reveal the address of the kernel function garp_pdu_rcv. Review whether users can create VLAN devices on GRE or other non-Ethernet interfaces.

UBUNTU-CVE-2025-21920: Medium severity ubuntu/linux vulnerability

Affected Software

Remediation

Event History

Frequently Asked Questions

What access does an attacker need to exploit this issue?

Which systems are realistically exposed?

Are normal VLAN configurations affected?

How can I check for signs of exploitation or exposure?

Company

Resources

Contact

Frequently Asked Questions

What access does an attacker need to exploit this issue?

Which systems are realistically exposed?

Are normal VLAN configurations affected?

How can I check for signs of exploitation or exposure?