CVE-2025-21971: net_sched: Prevent creation of classes with TC_H_ROOT
Published Apr 1, 2025
·Updated
In the Linux kernel, the following vulnerability has been resolved:
netsched: Prevent creation of classes with TCHROOT
The function qdisctreereducebacklog() uses TCHROOT as a termination condition when traversing up the qdisc tree to update parent backlog counters. However, if a class is created with classid TCHROOT, the traversal terminates prematurely at this class instead of reaching the actual root qdisc, causing parent statistics to be incorrectly maintained. In case of DRR, this could lead to a crash as reported by Mingi Cho.
Prevent the creation of any Qdisc class with classid TCHROOT (0xFFFFFFFF) across all qdisc types, as suggested by Jamal.
Affected Software
223 affected componentsFixes available
Linux Kernel
Linux Linux kernel>=2.6.26<5.4.292
Linux Linux kernel>=5.5<5.10.236
Linux Linux kernel>=5.11<5.15.180
Linux Linux kernel>=5.16<6.1.132
Linux Linux kernel>=6.2<6.6.84
Linux Linux kernel>=6.7<6.12.20
Linux Linux kernel>=6.13<6.13.8
Linux Linux kernel=2.6.25
Linux Linux kernel=6.14-rc1
Linux Linux kernel=6.14-rc2
Linux Linux kernel=6.14-rc3
Linux Linux kernel=6.14-rc4
Linux Linux kernel=6.14-rc5
Linux Linux kernel=6.14-rc6
ubuntu/linux*
ubuntu/linux-aws<4.4.0-1143.149
4.4.0-1143.149
ubuntu/linux-azure<4.15.0-1188.203~14.04.1
4.15.0-1188.203~14.04.1
ubuntu/linux-lts-xenial<4.4.0-268.302~14.04.1
4.4.0-268.302~14.04.1
ubuntu/linux<4.4.0-268.302
4.4.0-268.302
ubuntu/linux-aws<4.4.0-1181.196
4.4.0-1181.196
ubuntu/linux-aws-hwe<4.15.0-1180.193~16.04.1
4.15.0-1180.193~16.04.1
ubuntu/linux-azure<4.15.0-1188.203~16.04.1
4.15.0-1188.203~16.04.1
ubuntu/linux-gcp<4.15.0-1173.190~16.04.1
4.15.0-1173.190~16.04.1
ubuntu/linux-hwe<4.15.0-237.249~16.04.1
4.15.0-237.249~16.04.1
ubuntu/linux-kvm<4.4.0-1144.155
4.4.0-1144.155
ubuntu/linux-oracle<4.15.0-1142.153~16.04.1
4.15.0-1142.153~16.04.1
ubuntu/linux-hwe-edge*
ubuntu/linux-fips<4.4.0-1113.120
4.4.0-1113.120
ubuntu/linux-fips*
ubuntu/linux<4.15.0-237.249
4.15.0-237.249
ubuntu/linux-aws<4.15.0-1180.193
4.15.0-1180.193
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<4.15.0-1188.203
4.15.0-1188.203
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<4.15.0-1173.190
4.15.0-1173.190
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<4.15.0-1163.168
4.15.0-1163.168
ubuntu/linux-oem*
ubuntu/linux-oracle<4.15.0-1142.153
4.15.0-1142.153
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<4.15.0-2118.124
4.15.0-2118.124
ubuntu/linux-azure-fips<4.15.0-2097.103
4.15.0-2097.103
ubuntu/linux-fips<4.15.0-1135.146
4.15.0-1135.146
ubuntu/linux-gcp-fips<4.15.0-2081.87
4.15.0-2081.87
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<6.8.0-1029.31~22.04.1
6.8.0-1029.31~22.04.1
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<6.8.0-1029.34~22.04.1
6.8.0-1029.34~22.04.1
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<6.8.0-1030.32~22.04.1
6.8.0-1030.32~22.04.1
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<6.8.0-60.63~22.04.1
6.8.0-60.63~22.04.1
ubuntu/linux-ibm<5.15.0-1076.79
5.15.0-1076.79
ubuntu/linux-ibm-6.8<6.8.0-1026.26~22.04.1
6.8.0-1026.26~22.04.1
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<6.8.0-60.63.1~22.04.1
6.8.0-60.63.1~22.04.1
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<6.8.0-1028.31~22.04.1
6.8.0-1028.31~22.04.1
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<6.8.0-1026.27~22.04.1
6.8.0-1026.27~22.04.1
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<6.8.0-62.65~22.04.1
6.8.0-62.65~22.04.1
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<6.8.1-1022.23~22.04.1
6.8.1-1022.23~22.04.1
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<6.8.0-60.63
6.8.0-60.63
ubuntu/linux-aws<6.8.0-1029.31
6.8.0-1029.31
ubuntu/linux-azure<6.8.0-1029.34
6.8.0-1029.34
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<6.8.0-1016.17
6.8.0-1016.17
ubuntu/linux-gcp<6.8.0-1030.32
6.8.0-1030.32
ubuntu/linux-gcp-6.11<6.11.0-1015.15~24.04.1
6.11.0-1015.15~24.04.1
ubuntu/linux-gke<6.8.0-1025.29
6.8.0-1025.29
ubuntu/linux-gkeop<6.8.0-1012.14
6.8.0-1012.14
ubuntu/linux-hwe-6.11<6.11.0-26.26~24.04.1
6.11.0-26.26~24.04.1
ubuntu/linux-ibm<6.8.0-1026.26
6.8.0-1026.26
ubuntu/linux-lowlatency<6.8.0-60.63.1
6.8.0-60.63.1
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<6.8.0-1028.31
6.8.0-1028.31
ubuntu/linux-nvidia-6.11<6.11.0-1010.10
6.11.0-1010.10
ubuntu/linux-nvidia-lowlatency<6.8.0-1028.31.1
6.8.0-1028.31.1
ubuntu/linux-nvidia-tegra<6.8.0-1008.8
6.8.0-1008.8
ubuntu/linux-oem-6.11<6.11.0-1022.22
6.11.0-1022.22
ubuntu/linux-oem-6.8<6.8.0-1028.28
6.8.0-1028.28
ubuntu/linux-oracle<6.8.0-1026.27
6.8.0-1026.27
ubuntu/linux-raspi<6.8.0-1028.32
6.8.0-1028.32
ubuntu/linux-raspi-realtime*
ubuntu/linux-realtime*
ubuntu/linux-riscv<6.8.0-60.63.1
6.8.0-60.63.1
ubuntu/linux-xilinx<6.8.0-1017.18
6.8.0-1017.18
ubuntu/linux-raspi-realtime<6.8.0-2023.24
6.8.0-2023.24
ubuntu/linux-realtime<6.8.1-1022.23
6.8.1-1022.23
ubuntu/linux-fips<6.8.0-78.78+fips1
6.8.0-78.78+fips1
debian/linux
6.1.176-16.1.190-16.12.107-16.12.115-27.2.12-17.2.15-1
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
debian/linuxto a version that resolves this vulnerability.Fixed in 6.1.135-1Fixed in 6.12.25-1Fixed in 6.12.27-1 - Configuration
Prevent creation of any Qdisc class with classid TC_H_ROOT (0xFFFFFFFF) across all qdisc types (net_sched: prevent creation of classes with TC_H_ROOT).
Linux kernel net_sched (traffic control qdisc/classes) classid TC_H_ROOT (0xFFFFFFFF) = disallow/prevent creation
Event History
Apr 1, 2025
CVE Published
via MITRE·03:47 PM
Data Sourced
via MITRE·03:47 PM
DescriptionSeverity
Data Sourced
via OSV·04:15 PM
DescriptionSeverityAffected Software
Data Sourced
via NVD·04:15 PM
RemedyDescriptionSeverityWeaknessAffected Software
Frequently Asked Questions
1
What is the severity of CVE-2025-21971?
CVE-2025-21971 has been classified as a moderate severity vulnerability.
2
How do I fix CVE-2025-21971?
To fix CVE-2025-21971, you should update your Linux kernel to the latest stable version that includes the patch.
3
What systems are affected by CVE-2025-21971?
CVE-2025-21971 affects various versions of the Linux kernel.
4
What are the potential impacts of CVE-2025-21971?
The potential impact of CVE-2025-21971 includes disruptions in class creation within network scheduling in the kernel.
5
When was CVE-2025-21971 disclosed?
CVE-2025-21971 was disclosed alongside the resolution made to the Linux kernel managing network scheduling.