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Unscored CVE-2025-39766 EUVD-2025-28946GHSA-p46x-ph7h-c256

net/sched: Make cake_enqueue return NET_XMIT_CN when past buffer_limit

Published Sep 11, 2025 · Updated Jun 11, 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-6.14 Package: linux-aws-6.2 Package: linux-aws-6.5 Package: linux-aws-6.8 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-6.14 Package: linux-azure-6.2 Package: linux-azure-6.5 Package: linux-azure-6.8 Package: linux-azure-edge Package: linux-azure-fde Package: linux-azure-fde-5.19 Package: linux-azure-fde-6.14 Package: linux-azure-fde-6.2 Package: linux-azure-fde-6.8 Package: linux-azure-fips Package: linux-azure-nvidia Package: linux-azure-nvidia-6.14 Package: linux-bluefield Package: linux-fips Package: linux-gcp Package: linux-gcp-5.11 Package: linux-gcp-5.13 Package: linux-gcp-5.15 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-6.14 Package: linux-gcp-6.2 Package: linux-gcp-6.5 Package: linux-gcp-6.8 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-6.14 Package: linux-hwe-6.2 Package: linux-hwe-6.5 Package: linux-hwe-6.8 Package: linux-hwe-edge Package: linux-ibm Package: linux-ibm-5.15 Package: linux-ibm-5.4 Package: linux-ibm-6.8 Package: linux-intel Package: linux-intel-5.13 Package: linux-intel-iot-realtime Package: linux-intel-iotg Package: linux-intel-iotg-5.15 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-lowlatency-hwe-6.8 Package: linux-nvidia Package: linux-nvidia-6.11 Package: linux-nvidia-6.2 Package: linux-nvidia-6.5 Package: linux-nvidia-6.8 Package: linux-nvidia-lowlatency Package: linux-nvidia-tegra Package: linux-nvidia-tegra-5.15 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-6.14 Package: linux-oem-6.5 Package: linux-oem-6.8 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-6.14 Package: linux-oracle-6.5 Package: linux-oracle-6.8 Package: linux-raspi Package: linux-raspi-5.4 Package: linux-raspi-realtime Package: linux-raspi2 Package: linux-realtime Package: linux-realtime-6.14 Package: linux-realtime-6.8 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-6.14 Package: linux-riscv-6.5 Package: linux-riscv-6.8 Package: linux-starfive-5.19 Package: linux-starfive-6.2 Package: linux-starfive-6.5 Package: linux-vmware Package: linux-xilinx Package: linux-xilinx-zynqmp Platform: Linux Ecosystem: Azure Linux Ecosystem: Debian Ecosystem: Ubuntu

Description

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

net/sched: Make cake_enqueue return NET_XMIT_CN when past buffer_limit

The following setup can trigger a WARNING in htb_activate due to
the condition: !cl->leaf.q->q.qlen

tc qdisc del dev lo root
tc qdisc add dev lo root handle 1: htb default 1
tc class add dev lo parent 1: classid 1:1 \
htb rate 64bit
tc qdisc add dev lo parent 1:1 handle f: \
cake memlimit 1b
ping -I lo -f -c1 -s64 -W0.001 127.0.0.1

This is because the low memlimit leads to a low buffer_limit, which
causes packet dropping. However, cake_enqueue still returns
NET_XMIT_SUCCESS, causing htb_enqueue to call htb_activate with an
empty child qdisc. We should return NET_XMIT_CN when packets are
dropped from the same tin and flow.

I do not believe return value of NET_XMIT_CN is necessary for packet
drops in the case of ack filtering, as that is meant to optimize
performance, not to signal congestion.

Affected products

VendorProductAffectedFixed
Linux Linux 4.19 5.4.297

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 6.16.5-1 —
Debian 13 linux 6.12.48-1 DSA-6008-1
Debian 12 linux 6.1.153-1 DSA-6009-1
Debian 11 linux 5.10.244-1 DLA-4327-1
Debian 11 linux-6.1 6.1.153-1~deb11u1 DLA-4328-1
ReleasePackageFixed inAdvisory
Ubuntu Nvidia-BlueField 24.04 LTS linux-bluefield 6.8.0-1016.20 —
Ubuntu Nvidia-BlueField 22.04 LTS linux-bluefield 5.15.0-1081.83 —
Ubuntu 25.10 linux-azure-fde No fix yet —
Ubuntu 24.04 LTS linux 6.8.0-100.100 USN-8028-1
Ubuntu 24.04 LTS linux-aws +1 6.8.0-1046.49 USN-8028-5
Ubuntu 24.04 LTS linux-azure 6.8.0-1046.52 USN-8074-1
Ubuntu 24.04 LTS linux-azure-fde 6.8.0-1046.53 —
Ubuntu 24.04 LTS linux-azure-nvidia 6.8.0-1039.42 —
Ubuntu 24.04 LTS linux-gcp 6.8.0-1047.50 USN-8031-3
Ubuntu 24.04 LTS linux-gke 6.8.0-1043.48 USN-8031-3
Ubuntu 24.04 LTS linux-gkeop 6.8.0-1030.33 USN-8028-5
Ubuntu 24.04 LTS linux-ibm 6.8.0-1044.44 USN-8028-8
Ubuntu 24.04 LTS linux-intel +19 No fix yet —
Ubuntu 24.04 LTS linux-lowlatency 6.8.0-100.100.1 USN-8052-1
Ubuntu 24.04 LTS linux-nvidia-lowlatency 6.8.0-1046.49.1 USN-8028-7
Ubuntu 24.04 LTS linux-nvidia-tegra 6.8.0-1020.20 —
Ubuntu 24.04 LTS linux-oracle 6.8.0-1043.44 USN-8028-5
Ubuntu 24.04 LTS linux-raspi 6.8.0-1047.51 USN-8028-1
Ubuntu 24.04 LTS linux-xilinx 6.8.0-1023.24 USN-8052-2
Ubuntu 22.04 LTS linux +1 5.15.0-163.173 USN-7909-1
Ubuntu 22.04 LTS linux-aws 5.15.0-1097.104 USN-7909-1
Ubuntu 22.04 LTS linux-aws-6.8 +1 6.8.0-1046.49~22.04.1 USN-8028-5
Ubuntu 22.04 LTS linux-azure 5.15.0-1101.110 USN-7910-2
Ubuntu 22.04 LTS linux-azure-6.8 6.8.0-1051.57~22.04.1 USN-8126-1
Ubuntu 22.04 LTS linux-azure-fde 5.15.0-1102.111.1 —
Ubuntu 22.04 LTS linux-azure-fde-6.8 6.8.0-1046.53~22.04.1 —
Ubuntu 22.04 LTS linux-gcp 5.15.0-1097.106 USN-7909-4
Ubuntu 22.04 LTS linux-gcp-6.8 6.8.0-1047.50~22.04.2 USN-8031-1
Ubuntu 22.04 LTS linux-gke 5.15.0-1093.99 USN-7909-4
Ubuntu 22.04 LTS linux-gkeop 5.15.0-1080.88 USN-7909-4
Ubuntu 22.04 LTS linux-hwe-6.8 +1 6.8.0-100.100~22.04.1 USN-8028-6
Ubuntu 22.04 LTS linux-ibm +1 5.15.0-1091.94 USN-7909-5, USN-7909-1
Ubuntu 22.04 LTS linux-ibm-6.8 6.8.0-1044.44~22.04.1 USN-8028-8
Ubuntu 22.04 LTS linux-intel-iotg 5.15.0-1092.98 USN-7909-1
Ubuntu 22.04 LTS linux-kvm 5.15.0-1089.94 USN-7933-1
Ubuntu 22.04 LTS linux-lowlatency-hwe-6.8 6.8.0-100.100.1~22.04.1 USN-8028-6
Ubuntu 22.04 LTS linux-nvidia 5.15.0-1092.93 USN-7909-1
Ubuntu 22.04 LTS linux-nvidia-tegra 5.15.0-1049.49 USN-7909-1
Ubuntu 22.04 LTS linux-nvidia-tegra-igx 5.15.0-1038.38 USN-7909-1
Ubuntu 22.04 LTS linux-oracle 5.15.0-1094.100 USN-7909-1
Ubuntu 22.04 LTS linux-oracle-6.8 6.8.0-1043.44~22.04.1 USN-8028-5
Ubuntu 22.04 LTS linux-riscv +32 No fix yet —
Ubuntu 22.04 LTS linux-xilinx-zynqmp 5.15.0-1061.65 USN-7909-1
Show 12 more (older releases, extended support, other products)
ReleasePackageFixed inAdvisory
Ubuntu 20.04 LTS linux-gke +28 No fix yet —
Ubuntu 18.04 LTS linux-gcp +14 No fix yet —
Ubuntu 16.04 LTS linux-hwe-edge No fix yet —
Ubuntu Pro Realtime 24.04 LTS linux-raspi-realtime 6.8.0-2037.38 USN-8028-3
Ubuntu Pro Realtime 24.04 LTS linux-realtime 6.8.1-1041.42 USN-8028-3
Ubuntu Pro Realtime 24.04 LTS linux-realtime-6.14 No fix yet —
Ubuntu Pro Realtime 22.04 LTS linux-intel-iot-realtime 5.15.0-1089.91 USN-7909-2
Ubuntu Pro Realtime 22.04 LTS linux-realtime 5.15.0-1096.105 USN-7909-2
Ubuntu Pro Realtime 22.04 LTS linux-realtime-6.8 6.8.1-1041.42~22.04.1 USN-8028-2
Ubuntu Pro FIPS 20.04 LTS linux-fips +3 No fix yet —
Ubuntu Pro FIPS-updates 24.04 LTS linux-aws-fips 6.8.0-1046.49+fips1 USN-8028-4
Ubuntu Pro FIPS-updates 24.04 LTS linux-azure-fips 6.8.0-1046.52+fips1 USN-8074-2
Ubuntu Pro FIPS-updates 24.04 LTS linux-fips 6.8.0-100.100+fips1 USN-8028-4
Ubuntu Pro FIPS-updates 24.04 LTS linux-gcp-fips 6.8.0-1047.50+fips1 USN-8031-2
Ubuntu Pro FIPS-updates 22.04 LTS linux-aws-fips 5.15.0-1097.104+fips1 USN-7909-3
Ubuntu Pro FIPS-updates 22.04 LTS linux-azure-fips 5.15.0-1101.110+fips1 USN-7910-1
Ubuntu Pro FIPS-updates 22.04 LTS linux-fips 5.15.0-163.173+fips1 USN-7909-3
Ubuntu Pro FIPS-updates 22.04 LTS linux-gcp-fips 5.15.0-1097.106+fips1 USN-7909-3
Ubuntu Pro FIPS-updates 20.04 LTS linux-fips +3 No fix yet —
Ubuntu Pro FIPS-preview 22.04 LTS linux-fips +3 No fix yet —
Ubuntu Pro 20.04 LTS linux +10 No fix yet —
Ubuntu Pro 20.04 LTS linux-aws-5.15 5.15.0-1097.104~20.04.1 USN-7909-1
Ubuntu Pro 20.04 LTS linux-azure-5.15 5.15.0-1102.111~20.04.1 USN-7938-1
Ubuntu Pro 20.04 LTS linux-gcp-5.15 5.15.0-1097.106~20.04.1 USN-7909-1
Ubuntu Pro 20.04 LTS linux-hwe-5.15 +1 5.15.0-163.173~20.04.1 USN-7909-1
Ubuntu Pro 20.04 LTS linux-ibm-5.15 5.15.0-1091.94~20.04.1 USN-7909-1
Ubuntu Pro 20.04 LTS linux-intel-iotg-5.15 5.15.0-1092.98~20.04.1 USN-7909-1
Ubuntu Pro 20.04 LTS linux-nvidia-tegra-5.15 5.15.0-1049.49~20.04.1 USN-7909-1
Ubuntu Pro 20.04 LTS linux-oracle-5.15 5.15.0-1094.100~20.04.1 USN-7909-1
Ubuntu Pro 20.04 LTS linux-riscv-5.15 5.15.0-1092.96~20.04.1 —
Ubuntu Pro 18.04 LTS linux-aws-5.4 +6 No fix yet —
ReleasePackageFixed inAdvisory
RHEL 10 rv +76 6.12.0-124.52.1.el10_1 RHSA-2026:19569, RHSA-2026:9264
RHEL 9 rv +75 5.14.0-611.49.1.el9_7 RHSA-2026:19568, RHSA-2026:8921
Show 4 more (older releases, extended support, other products)
ReleasePackageFixed inAdvisory
RHEL 10.0 EUS rv +77 6.12.0-55.76.1.el10_0 RHSA-2026:22334
RHEL 9.6 EUS rv +77 5.14.0-570.119.1.el9_6 RHSA-2026:23224
RHEL 9.4 EUS bpftool 7.3.0-427.127.1.el9_4 RHSA-2026:21209
RHEL 9.4 EUS rv +64 5.14.0-427.127.1.el9_4 RHSA-2026:21209
RHEL 9.2 E4S bpftool 7.0.0-284.174.1.el9_2 RHSA-2026:22940
RHEL 9.2 E4S kernel-rt +14 5.14.0-284.174.1.rt14.459.el9_2 RHSA-2026:22900
RHEL 9.2 E4S perf +47 5.14.0-284.174.1.el9_2 RHSA-2026:22940

AlmaLinux

Errata ↗
ReleasePackageFixed inAdvisory
AlmaLinux 10 kernel-doc +1 6.12.0-124.52.1.el10_1 ALSA-2026:19569, ALSA-2026:9264
AlmaLinux 10 rv +72 6.12.0-211.16.1.el10_2 ALSA-2026:19569
AlmaLinux 9 rv +73 5.14.0-611.49.1.el9_7 ALSA-2026:19568, ALSA-2026:8921

Rocky Linux

Errata ↗
ReleasePackageFixed inAdvisory
Rocky Linux 10 kernel 6.12.0-124.52.1.el10_1 RLSA-2026:19569, RLSA-2026:9264
Rocky Linux 9 kernel 5.14.0-611.49.1.el9_7 RLSA-2026:19568, RLSA-2026:8921
ReleasePackageFixed inAdvisory
SLES 15 SP7 kernel-64kb +6 6.4.0-150700.53.19.1 SUSE-SU-2025:03601-1
SLES 15 SP7 kernel-azure +1 6.4.0-150700.20.15.2 SUSE-SU-2025:03633-1
SLES 15 SP7 kernel-default-base 6.4.0-150700.53.19.1.150700.17.13.1 SUSE-SU-2025:03601-1
SLES 15 SP7 kernel-syms-azure 6.4.0-150700.20.15.1 SUSE-SU-2025:03633-1
SLES 15 SP6 kernel-64kb +6 6.4.0-150600.23.73.1 SUSE-SU-2025:03600-1
SLES 15 SP6 kernel-azure +2 6.4.0-150600.8.52.1 SUSE-SU-2025:03634-1
SLES 15 SP6 kernel-default-base 6.4.0-150600.23.73.1.150600.12.32.1 SUSE-SU-2025:03600-1
Show 9 more (older releases, extended support, other products)
ReleasePackageFixed inAdvisory
SLES for SAP 16.0 kernel-64kb +7 6.12.0-160000.6.1 SUSE-SU-2025:21139-1
SLES for SAP 16.0 kernel-default-base 6.12.0-160000.6.1.160000.2.4 SUSE-SU-2025:21139-1
SLES 16.0 kernel-64kb +7 6.12.0-160000.6.1 SUSE-SU-2025:21179-1, SUSE-SU-2025:21139-1
SLES 16.0 kernel-default-base 6.12.0-160000.6.1.160000.2.4 SUSE-SU-2025:21139-1
SLE Micro 6.2 kernel-default-base 6.12.0-160000.6.1.160000.2.4 SUSE-SU-2025:21074-1
SLE Micro 6.2 kernel-rt +5 6.12.0-160000.6.1 SUSE-SU-2026:20560-1, SUSE-SU-2025:21074-1
SLE Micro 6.1 kernel-default-base 6.4.0-35.1.21.12 SUSE-SU-2025:20861-1
SLE Micro 6.1 kernel-rt +1 6.4.0-37.1 SUSE-SU-2025:20898-1
SLE Micro 6.1 kernel-source +2 6.4.0-35.1 SUSE-SU-2025:20861-1
SLE Micro 6.0 kernel-default-base 6.4.0-35.1.21.12 SUSE-SU-2025:20851-1
SLE Micro 6.0 kernel-rt +1 6.4.0-37.1 SUSE-SU-2025:20870-1
SLE Micro 6.0 kernel-source +2 6.4.0-35.1 SUSE-SU-2025:20851-1
SLE Live Patching 15 SP7 kernel-default 6.4.0-150700.53.19.1 SUSE-SU-2025:03601-1
SLE Live Patching 15 SP7 kernel-livepatch-SLE15-SP7-RT_Update_5 1-150700.1.3.1 SUSE-SU-2025:3725-1
SLE Live Patching 15 SP7 kernel-livepatch-SLE15-SP7_Update_5 1-150700.15.3.1 SUSE-SU-2025:03601-1
SLE Live Patching 15 SP6 kernel-default 6.4.0-150600.23.73.1 SUSE-SU-2025:03600-1
SLE Live Patching 15 SP6 kernel-livepatch-SLE15-SP6-RT_Update_16 1-150600.1.3.1 SUSE-SU-2025:3751-1
SLE Live Patching 15 SP6 kernel-livepatch-SLE15-SP6_Update_16 1-150600.13.3.1 SUSE-SU-2025:03600-1
SUSE Real Time Module 15 SP7 kernel-rt +2 6.4.0-150700.7.19.1 SUSE-SU-2025:3725-1
SUSE Real Time Module 15 SP6 kernel-rt +3 6.4.0-150600.10.55.1 SUSE-SU-2025:3751-1
ReleasePackageFixed inAdvisory
openSUSE Leap 16.0 kernel-default-base 6.12.0-160000.6.1.160000.2.4 openSUSE-SU-2025:20081-1
openSUSE Leap 16.0 kernel-rt +10 6.12.0-160000.6.1 openSUSE-SU-2025:20081-1
openSUSE Leap 15.6 dtb-aarch64 +10 6.4.0-150600.23.73.1 SUSE-SU-2025:03600-1
openSUSE Leap 15.6 kernel-azure +2 6.4.0-150600.8.52.1 SUSE-SU-2025:03634-1
openSUSE Leap 15.6 kernel-default-base 6.4.0-150600.23.73.1.150600.12.32.1 SUSE-SU-2025:03600-1
openSUSE Leap 15.6 kernel-rt +3 6.4.0-150600.10.55.1 SUSE-SU-2025:3751-1

Amazon Linux

ReleasePackageFixed inAdvisory
Amazon Linux 2023 kernel-livepatch-6.12.46-66.121 +1 1:1.0-0.amzn2023 ALAS2023-2025-1208, ALAS2023-2025-1186
Amazon Linux 2023 perf +14 1:6.1.150-174.273.amzn2023 ALAS2023-2025-1186
Amazon Linux 2023 perf6.12 +14 1:6.12.46-66.121.amzn2023 ALAS2023-2025-1208

Azure Linux

ReleasePackageFixed inAdvisory
Azure Linux 3 kernel 6.6.104.2-1 —
Azure Linux 2 (CBL-Mariner) kernel 5.15.200.1-1 —

Oracle Linux

ReleasePackageFixed inAdvisory
Oracle Linux 10 rv +29 6.12.0-124.52.1.el10_1 ELSA-2026-19569, ELSA-2026-9264
Oracle Linux 9 kernel-uek +34 6.12.0-105.51.5.el10uek ELSA-2025-25754
Oracle Linux 9 rv +28 5.14.0-611.49.1.el9_7 ELSA-2026-19568, ELSA-2026-8921
Oracle Linux 8 bpftool +18 5.15.0-314.193.5.3.el9uek ELSA-2025-25757
Oracle Linux 7 kernel-uek +6 5.4.17-2136.348.3.el8uek ELSA-2025-20663
Oracle Linux 7 kernel-uek-tools 5.4.17-2136.348.3.el7uek ELSA-2025-20663

Advisories 50

References