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OpenAdvisories
High · 7.8 CVE-2025-21703 EUVD-2025-4525GHSA-cg86-m5xc-jqrm

netem: Update sch->q.qlen before qdisc_tree_reduce_backlog()

Published Feb 18, 2025 · Updated Oct 15, 2026 · Assigned by Linux

Vendor: Linux Product: Linux Package: kernel Package: linux Package: linux Package: linux-allwinner-5.19 Package: linux-aws Package: linux-aws-5.0 Package: linux-aws-5.11 Package: linux-aws-5.13 Package: linux-aws-5.15 Package: linux-aws-5.19 Package: linux-aws-5.3 Package: linux-aws-5.4 Package: linux-aws-5.8 Package: linux-aws-6.2 Package: linux-aws-6.5 Package: linux-aws-fips Package: linux-azure Package: linux-azure-5.11 Package: linux-azure-5.13 Package: linux-azure-5.15 Package: linux-azure-5.19 Package: linux-azure-5.3 Package: linux-azure-5.4 Package: linux-azure-5.8 Package: linux-azure-6.11 Package: linux-azure-6.2 Package: linux-azure-6.5 Package: linux-azure-edge Package: linux-azure-fde Package: linux-azure-fde-5.19 Package: linux-azure-fde-6.2 Package: linux-azure-fips Package: linux-bluefield Package: linux-fips Package: linux-gcp Package: linux-gcp-5.11 Package: linux-gcp-5.13 Package: linux-gcp-5.19 Package: linux-gcp-5.3 Package: linux-gcp-5.4 Package: linux-gcp-5.8 Package: linux-gcp-6.11 Package: linux-gcp-6.2 Package: linux-gcp-6.5 Package: linux-gcp-fips Package: linux-gke Package: linux-gke-4.15 Package: linux-gke-5.15 Package: linux-gke-5.4 Package: linux-gkeop Package: linux-gkeop-5.15 Package: linux-gkeop-5.4 Package: linux-hwe Package: linux-hwe-5.11 Package: linux-hwe-5.13 Package: linux-hwe-5.15 Package: linux-hwe-5.19 Package: linux-hwe-5.4 Package: linux-hwe-5.8 Package: linux-hwe-6.11 Package: linux-hwe-6.2 Package: linux-hwe-6.5 Package: linux-hwe-edge Package: linux-ibm Package: linux-intel-5.13 Package: linux-intel-iot-realtime Package: linux-intel-iotg Package: linux-iot Package: linux-kvm Package: linux-lowlatency Package: linux-lowlatency-hwe-5.15 Package: linux-lowlatency-hwe-5.19 Package: linux-lowlatency-hwe-6.11 Package: linux-lowlatency-hwe-6.2 Package: linux-lowlatency-hwe-6.5 Package: linux-nvidia Package: linux-nvidia-6.2 Package: linux-nvidia-6.5 Package: linux-nvidia-tegra Package: linux-nvidia-tegra-igx Package: linux-oem Package: linux-oem-5.10 Package: linux-oem-5.13 Package: linux-oem-5.14 Package: linux-oem-5.17 Package: linux-oem-5.6 Package: linux-oem-6.0 Package: linux-oem-6.1 Package: linux-oem-6.11 Package: linux-oem-6.5 Package: linux-oracle Package: linux-oracle-5.0 Package: linux-oracle-5.11 Package: linux-oracle-5.13 Package: linux-oracle-5.15 Package: linux-oracle-5.3 Package: linux-oracle-5.4 Package: linux-oracle-5.8 Package: linux-oracle-6.5 Package: linux-raspi Package: linux-raspi-realtime Package: linux-raspi2 Package: linux-realtime Package: linux-riscv Package: linux-riscv-5.11 Package: linux-riscv-5.15 Package: linux-riscv-5.19 Package: linux-riscv-5.8 Package: linux-riscv-6.5 Package: linux-starfive-5.19 Package: linux-starfive-6.2 Package: linux-starfive-6.5 Package: linux-xilinx-zynqmp Platform: Linux Ecosystem: Azure Linux Ecosystem: Debian Ecosystem: Ubuntu

Description

In the Linux kernel, the following vulnerability has been resolved:

netem: Update sch->q.qlen before qdisc_tree_reduce_backlog()

qdisc_tree_reduce_backlog() notifies parent qdisc only if child
qdisc becomes empty, therefore we need to reduce the backlog of the
child qdisc before calling it. Otherwise it would miss the opportunity
to call cops->qlen_notify(), in the case of DRR, it resulted in UAF
since DRR uses ->qlen_notify() to maintain its active list.

Affected products

VendorProductAffectedFixed
Linux Linux 5.4.288 – < 5.4.291, 5.10.232 – < 5.10.235, 5.15.175 – < 5.15.179, 6.1.121 – < 6.1.129, 6.6.67 – < 6.6.78, 6.12.6 – < 6.12.14, 6.13 5.4.291

Fixed in Linux distributions

Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.

ReleasePackageFixed inAdvisory
Debian 14 linux 6.12.15-1 —
Debian 13 linux 6.12.15-1 —
Debian 12 linux 6.1.129-1 —
Debian 11 linux-6.1 6.1.129-1~deb11u1 DLA-4102-1
ReleasePackageFixed inAdvisory
Ubuntu Nvidia-BlueField 22.04 LTS linux-bluefield 5.15.0-1064.66 —
Ubuntu 24.04 LTS linux-gcp-6.11 +1 6.11.0-1013.13~24.04.1 USN-7448-1
Ubuntu 24.04 LTS linux-hwe-6.11 6.11.0-24.24~24.04.1 USN-7445-1
Ubuntu 24.04 LTS linux-lowlatency-hwe-6.11 6.11.0-1012.13~24.04.1 USN-7445-1
Ubuntu 24.04 LTS linux-oem-6.11 6.11.0-1020.20 USN-7445-1
Ubuntu 24.04 LTS linux-raspi-realtime No fix yet —
Ubuntu 22.04 LTS linux +1 5.15.0-138.148 USN-7455-1
Ubuntu 22.04 LTS linux-aws 5.15.0-1082.89 USN-7455-1
Ubuntu 22.04 LTS linux-azure 5.15.0-1087.96 USN-7455-1
Ubuntu 22.04 LTS linux-azure-fde 5.15.0-1087.96.1 USN-7455-1
Ubuntu 22.04 LTS linux-gcp 5.15.0-1081.90 USN-7455-1
Ubuntu 22.04 LTS linux-gke +1 5.15.0-1079.85 USN-7455-1
Ubuntu 22.04 LTS linux-gkeop 5.15.0-1064.72 USN-7455-1
Ubuntu 22.04 LTS linux-ibm 5.15.0-1074.77 USN-7455-1
Ubuntu 22.04 LTS linux-intel-iotg 5.15.0-1077.83 USN-7455-1
Ubuntu 22.04 LTS linux-kvm 5.15.0-1078.83 USN-7455-1
Ubuntu 22.04 LTS linux-nvidia 5.15.0-1076.77 USN-7455-1
Ubuntu 22.04 LTS linux-nvidia-tegra 5.15.0-1035.35 USN-7455-1
Ubuntu 22.04 LTS linux-nvidia-tegra-igx 5.15.0-1023.23 USN-7455-1
Ubuntu 22.04 LTS linux-raspi 5.15.0-1076.79 USN-7455-1
Ubuntu 22.04 LTS linux-riscv +32 No fix yet —
Ubuntu 22.04 LTS linux-xilinx-zynqmp 5.15.0-1046.50 USN-7475-1
Ubuntu 20.04 LTS linux 5.4.0-214.234 USN-7461-1
Ubuntu 20.04 LTS linux-aws 5.4.0-1144.154 USN-7462-1
Ubuntu 20.04 LTS linux-aws-5.15 5.15.0-1082.89~20.04.1 USN-7455-5
Ubuntu 20.04 LTS linux-azure 5.4.0-1149.156 USN-7461-1
Ubuntu 20.04 LTS linux-azure-5.15 5.15.0-1087.96~20.04.1 USN-7455-1
Ubuntu 20.04 LTS linux-azure-fde-5.15 5.15.0-1087.96~20.04.1.1 USN-7455-1
Ubuntu 20.04 LTS linux-bluefield 5.4.0-1103.110 USN-7461-1
Ubuntu 20.04 LTS linux-gcp 5.4.0-1147.156 USN-7461-1
Ubuntu 20.04 LTS linux-gcp-5.15 5.15.0-1081.90~20.04.1 USN-7459-2
Ubuntu 20.04 LTS linux-gke +28 No fix yet —
Ubuntu 20.04 LTS linux-hwe-5.15 +1 5.15.0-138.148~20.04.1 USN-7455-1
Ubuntu 20.04 LTS linux-ibm 5.4.0-1090.95 USN-7461-1
Ubuntu 20.04 LTS linux-intel-iotg-5.15 5.15.0-1077.83~20.04.1 USN-7459-1
Ubuntu 20.04 LTS linux-iot 5.4.0-1049.52 USN-7462-1
Ubuntu 20.04 LTS linux-kvm 5.4.0-1131.140 USN-7461-1
Ubuntu 20.04 LTS linux-oracle 5.4.0-1142.152 USN-7461-1
Ubuntu 20.04 LTS linux-oracle-5.15 5.15.0-1079.85~20.04.1 USN-7455-4
Ubuntu 20.04 LTS linux-riscv-5.15 5.15.0-1077.81~20.04.1 —
Ubuntu 20.04 LTS linux-xilinx-zynqmp 5.4.0-1062.66 USN-7461-3
Ubuntu 18.04 LTS linux-gcp +14 No fix yet —
Show 5 more (older releases, extended support, other products)
ReleasePackageFixed inAdvisory
Ubuntu 16.04 LTS linux-hwe-edge No fix yet —
Ubuntu Pro Realtime 22.04 LTS linux-intel-iot-realtime 5.15.0-1075.77 USN-7455-3
Ubuntu Pro Realtime 22.04 LTS linux-realtime 5.15.0-1082.91 USN-7455-3
Ubuntu Pro FIPS-updates 22.04 LTS linux-aws-fips 5.15.0-1082.89+fips1 USN-7455-2
Ubuntu Pro FIPS-updates 22.04 LTS linux-azure-fips 5.15.0-1087.96+fips1 USN-7460-1
Ubuntu Pro FIPS-updates 22.04 LTS linux-fips 5.15.0-138.148+fips1 USN-7455-2
Ubuntu Pro FIPS-updates 22.04 LTS linux-gcp-fips 5.15.0-1081.90+fips1 USN-7455-2
Ubuntu Pro FIPS-updates 20.04 LTS linux-aws-fips 5.4.0-1144.155+fips1 USN-7462-2
Ubuntu Pro FIPS-updates 20.04 LTS linux-azure-fips 5.4.0-1149.157+fips1 USN-7461-2
Ubuntu Pro FIPS-updates 20.04 LTS linux-fips 5.4.0-1118.128 USN-7461-2
Ubuntu Pro FIPS-updates 20.04 LTS linux-gcp-fips 5.4.0-1147.156+fips1 USN-7461-2
Ubuntu Pro 18.04 LTS linux-aws-5.4 5.4.0-1144.154~18.04.1 USN-7462-1
Ubuntu Pro 18.04 LTS linux-azure-5.4 5.4.0-1149.156~18.04.1 USN-7461-1
Ubuntu Pro 18.04 LTS linux-gcp-5.4 5.4.0-1147.156~18.04.1 USN-7462-1
Ubuntu Pro 18.04 LTS linux-hwe-5.4 5.4.0-214.234~18.04.1 USN-7461-1
Ubuntu Pro 18.04 LTS linux-oracle-5.4 5.4.0-1142.152~18.04.1 USN-7461-1
ReleasePackageFixed inAdvisory
SLES 15 SP7 kernel-64kb +6 6.4.0-150700.53.3.1 SUSE-SU-2025:01951-1
SLES 15 SP7 kernel-azure +2 6.4.0-150700.20.3.1 SUSE-SU-2025:01967-1
SLES 15 SP7 kernel-default-base 6.4.0-150700.53.3.1.150700.17.2.1 SUSE-SU-2025:01951-1
SLES 15 SP6 kernel-64kb +3 6.4.0-150600.23.47.2 SUSE-SU-2025:1180-1
SLES 15 SP6 kernel-azure +1 6.4.0-150600.8.34.2 SUSE-SU-2025:1177-1
SLES 15 SP6 kernel-coco +3 6.4.0-15061.21.coco15sp6.1 SUSE-SU-2025:01919-1
SLES 15 SP6 kernel-default-base 6.4.0-150600.23.47.2.150600.12.20.2 SUSE-SU-2025:1180-1
SLES 15 SP6 kernel-docs +2 6.4.0-150600.23.47.1 SUSE-SU-2025:1180-1
SLES 15 SP6 kernel-syms-azure 6.4.0-150600.8.34.1 SUSE-SU-2025:1177-1
SLES 15 SP5 kernel-64kb +6 5.14.21-150500.55.113.1 SUSE-SU-2025:02264-1
SLES 15 SP5 kernel-default-base 5.14.21-150500.55.113.1.150500.6.53.1 SUSE-SU-2025:02264-1
SLES 15 SP4 kernel-64kb +3 5.14.21-150400.24.170.2 SUSE-SU-2025:02537-1
SLES 15 SP4 kernel-default-base 5.14.21-150400.24.170.2.150400.24.86.2 SUSE-SU-2025:02537-1
SLES 15 SP4 kernel-docs +2 5.14.21-150400.24.170.1 SUSE-SU-2025:02537-1
SLES 15 SP3 kernel-64kb +6 5.3.18-150300.59.211.1 SUSE-SU-2025:02308-1
SLES 15 SP3 kernel-default-base 5.3.18-150300.59.211.1.150300.18.126.1 SUSE-SU-2025:02308-1
SLES 15 SP3 kernel-obs-build 5.3.18-150300.59.212.1 SUSE-SU-2025:02308-1
Show 22 more (older releases, extended support, other products)
ReleasePackageFixed inAdvisory
SLES 12 SP5 kernel-syms +2 4.12.14-122.255.1 SUSE-SU-2025:1293-1
SLES for SAP 15 SP5 kernel-default-base 5.14.21-150500.55.113.1.150500.6.53.1 SUSE-SU-2025:02264-1
SLES for SAP 15 SP5 kernel-docs +4 5.14.21-150500.55.113.1 SUSE-SU-2025:02264-1
SLES for SAP 15 SP4 kernel-default +1 5.14.21-150400.24.170.2 SUSE-SU-2025:02537-1
SLES for SAP 15 SP4 kernel-default-base 5.14.21-150400.24.170.2.150400.24.86.2 SUSE-SU-2025:02537-1
SLES for SAP 15 SP4 kernel-docs +2 5.14.21-150400.24.170.1 SUSE-SU-2025:02537-1
SLES for SAP 15 SP3 kernel-default-base 5.3.18-150300.59.211.1.150300.18.126.1 SUSE-SU-2025:02308-1
SLES for SAP 15 SP3 kernel-docs +4 5.3.18-150300.59.211.1 SUSE-SU-2025:02308-1
SLES for SAP 15 SP3 kernel-obs-build 5.3.18-150300.59.212.1 SUSE-SU-2025:02308-1
SLE Micro 6.1 kernel-default-base 6.4.0-28.1.21.6 SUSE-SU-2025:20270-1
SLE Micro 6.1 kernel-livepatch-MICRO-6-0_Update_6 +1 1-3.1 SUSE-SU-2025:20270-1, SUSE-SU-2025:20260-1
SLE Micro 6.1 kernel-rt +4 6.4.0-28.1 SUSE-SU-2025:20270-1, SUSE-SU-2025:20260-1
SLE Micro 6.0 kernel-default-base 6.4.0-28.1.21.6 SUSE-SU-2025:20192-1
SLE Micro 6.0 kernel-livepatch-MICRO-6-0_Update_6 +1 1-3.1 SUSE-SU-2025:20192-1, SUSE-SU-2025:20190-1
SLE Micro 6.0 kernel-rt +4 6.4.0-28.1 SUSE-SU-2025:20192-1, SUSE-SU-2025:20190-1
SLE Micro 5.5 kernel-default-base 5.14.21-150500.55.113.1.150500.6.53.1 SUSE-SU-2025:02264-1
SLE Micro 5.5 kernel-rt 5.14.21-150500.13.100.2 SUSE-SU-2025:02321-1
SLE Micro 5.5 kernel-source +1 5.14.21-150500.55.113.1 SUSE-SU-2025:02264-1
SLE Micro 5.5 kernel-source-rt 5.14.21-150500.13.100.1 SUSE-SU-2025:02321-1
SLE Micro 5.4 kernel-default 5.14.21-150400.24.170.2 SUSE-SU-2025:02537-1
SLE Micro 5.4 kernel-default-base 5.14.21-150400.24.170.2.150400.24.86.2 SUSE-SU-2025:02537-1
SLE Micro 5.4 kernel-rt +1 5.14.21-150400.15.124.1 SUSE-SU-2025:02322-1
SLE Micro 5.3 kernel-default 5.14.21-150400.24.170.2 SUSE-SU-2025:02537-1
SLE Micro 5.3 kernel-default-base 5.14.21-150400.24.170.2.150400.24.86.2 SUSE-SU-2025:02537-1
SLE Micro 5.3 kernel-rt +1 5.14.21-150400.15.124.1 SUSE-SU-2025:02322-1
SLE Micro 5.2 kernel-default 5.3.18-150300.59.211.1 SUSE-SU-2025:02308-1
SLE Micro 5.2 kernel-default-base 5.3.18-150300.59.211.1.150300.18.126.1 SUSE-SU-2025:02308-1
SLE Micro 5.2 kernel-rt +1 5.3.18-150300.214.1 SUSE-SU-2025:02320-1
SLE Micro 5.1 kernel-default 5.3.18-150300.59.211.1 SUSE-SU-2025:02308-1
SLE Micro 5.1 kernel-default-base 5.3.18-150300.59.211.1.150300.18.126.1 SUSE-SU-2025:02308-1
SLE Micro 5.1 kernel-rt +1 5.3.18-150300.214.1 SUSE-SU-2025:02320-1
SLE Live Patching 15 SP7 kernel-default 6.4.0-150700.53.3.1 SUSE-SU-2025:01951-1
SLE Live Patching 15 SP7 kernel-livepatch-SLE15-SP7_Update_1 1-150700.15.3.1 SUSE-SU-2025:01951-1
SLE Live Patching 15 SP6 kernel-default 6.4.0-150600.23.47.2 SUSE-SU-2025:1180-1
SLE Live Patching 15 SP6 kernel-livepatch-SLE15-SP6-RT_Update_10 1-150600.1.5.1 SUSE-SU-2025:1178-1
SLE Live Patching 15 SP6 kernel-livepatch-SLE15-SP6_Update_10 1-150600.13.5.1 SUSE-SU-2025:1180-1
SLE Live Patching 15 SP5 kernel-default 5.14.21-150500.55.113.1 SUSE-SU-2025:02264-1
SLE Live Patching 15 SP5 kernel-livepatch-SLE15-SP5_Update_28 1-150500.11.3.1 SUSE-SU-2025:02264-1
SLE Live Patching 15 SP3 kernel-default 5.3.18-150300.59.211.1 SUSE-SU-2025:02308-1
SLE Live Patching 15 SP3 kernel-livepatch-SLE15-SP3_Update_59 1-150300.7.3.1 SUSE-SU-2025:02308-1
SLE Live Patching 12 SP5 kernel-default 4.12.14-122.255.1 SUSE-SU-2025:1293-1
SLE Live Patching 12 SP5 kgraft-patch-SLE12-SP5_Update_67 1-8.5.1 SUSE-SU-2025:1293-1
SLE HPC 15 SP5 kernel-64kb +5 5.14.21-150500.55.113.1 SUSE-SU-2025:02264-1
SLE HPC 15 SP5 kernel-default-base 5.14.21-150500.55.113.1.150500.6.53.1 SUSE-SU-2025:02264-1
SLE HPC 15 SP4 kernel-64kb +2 5.14.21-150400.24.170.2 SUSE-SU-2025:02537-1
SLE HPC 15 SP4 kernel-default-base 5.14.21-150400.24.170.2.150400.24.86.2 SUSE-SU-2025:02537-1
SLE HPC 15 SP4 kernel-docs +2 5.14.21-150400.24.170.1 SUSE-SU-2025:02537-1
SUSE Real Time Module 15 SP6 kernel-rt +3 6.4.0-150600.10.34.1 SUSE-SU-2025:1178-1
SUSE Manager Server 4.3 kernel-default +1 5.14.21-150400.24.170.2 SUSE-SU-2025:02537-1
SUSE Manager Server 4.3 kernel-default-base 5.14.21-150400.24.170.2.150400.24.86.2 SUSE-SU-2025:02537-1
SUSE Manager Server 4.3 kernel-syms +1 5.14.21-150400.24.170.1 SUSE-SU-2025:02537-1
SUSE Manager Proxy 4.3 kernel-default 5.14.21-150400.24.170.2 SUSE-SU-2025:02537-1
SUSE Manager Proxy 4.3 kernel-default-base 5.14.21-150400.24.170.2.150400.24.86.2 SUSE-SU-2025:02537-1
SUSE Manager Proxy 4.3 kernel-syms +1 5.14.21-150400.24.170.1 SUSE-SU-2025:02537-1
SUSE Enterprise Storage 7.1 kernel-64kb +5 5.3.18-150300.59.211.1 SUSE-SU-2025:02308-1
SUSE Enterprise Storage 7.1 kernel-default-base 5.3.18-150300.59.211.1.150300.18.126.1 SUSE-SU-2025:02308-1
SUSE Enterprise Storage 7.1 kernel-obs-build 5.3.18-150300.59.212.1 SUSE-SU-2025:02308-1
ReleasePackageFixed inAdvisory
openSUSE Leap 15.6 dtb-aarch64 +4 6.4.0-150600.23.47.1 SUSE-SU-2025:1180-1
openSUSE Leap 15.6 kernel-64kb +5 6.4.0-150600.23.47.2 SUSE-SU-2025:1180-1
openSUSE Leap 15.6 kernel-azure +1 6.4.0-150600.8.34.2 SUSE-SU-2025:1177-1
openSUSE Leap 15.6 kernel-default-base 6.4.0-150600.23.47.2.150600.12.20.2 SUSE-SU-2025:1180-1
openSUSE Leap 15.6 kernel-rt +3 6.4.0-150600.10.34.1 SUSE-SU-2025:1178-1
openSUSE Leap 15.6 kernel-syms-azure 6.4.0-150600.8.34.1 SUSE-SU-2025:1177-1

Amazon Linux

ReleasePackageFixed inAdvisory
Amazon Linux 2023 kernel-livepatch-6.1.129-138.220 1.0-0.amzn2023 ALAS2023-2025-876
Amazon Linux 2023 perf +14 6.1.129-138.220.amzn2023 ALAS2023-2025-876

Azure Linux

ReleasePackageFixed inAdvisory
Azure Linux 2 (CBL-Mariner) kernel 5.15.180.1-1 —

Oracle Linux

ReleasePackageFixed inAdvisory
Oracle Linux 9 kernel-uek +34 6.12.0-101.33.4.3.el10uek ELSA-2025-20530, ELSA-2025-20480

Advisories 44

References