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Unscored CVE-2026-74284 EUVD-2026-59431GHSA-mfhv-3jvw-9w4g

net/sched: sch_hfsc: Don't make class passive twice

Published Aug 15, 2026 · Updated Nov 6, 2026 · Assigned by Linux

Vendor: Linux Product: Linux 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-6.17 Package: linux-aws-6.2 Package: linux-aws-6.5 Package: linux-aws-6.8 Package: linux-aws-7.0 Package: linux-aws-fips Package: linux-aws-hwe Package: linux-azure Package: linux-azure-4.15 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-6.17 Package: linux-azure-6.2 Package: linux-azure-6.5 Package: linux-azure-6.8 Package: linux-azure-7.0 Package: linux-azure-edge Package: linux-azure-fde Package: linux-azure-fde-5.15 Package: linux-azure-fde-5.19 Package: linux-azure-fde-6.14 Package: linux-azure-fde-6.17 Package: linux-azure-fde-6.2 Package: linux-azure-fde-6.8 Package: linux-azure-fde-7.0 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-4.15 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-6.17 Package: linux-gcp-6.2 Package: linux-gcp-6.5 Package: linux-gcp-6.8 Package: linux-gcp-7.0 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-6.17 Package: linux-hwe-6.2 Package: linux-hwe-6.5 Package: linux-hwe-6.8 Package: linux-hwe-7.0 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-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-lts-xenial Package: linux-nvidia Package: linux-nvidia-6.11 Package: linux-nvidia-6.17 Package: linux-nvidia-6.2 Package: linux-nvidia-6.5 Package: linux-nvidia-6.8 Package: linux-nvidia-7.0 Package: linux-nvidia-bos 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-6.17 Package: linux-oem-6.5 Package: linux-oem-6.8 Package: linux-oem-7.0 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-6.17 Package: linux-oracle-6.5 Package: linux-oracle-6.8 Package: linux-oracle-7.0 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-6.17 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-6.17 Package: linux-riscv-6.5 Package: linux-riscv-6.8 Package: linux-riscv-7.0 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: Debian Ecosystem: Ubuntu

Description

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

net/sched: sch_hfsc: Don't make class passive twice

update_vf() is called from two places for the same class during a single
dequeue when the class's child qdisc (e.g. codel/fq_codel) drops its last
packets while dequeuing:

1. The child calls qdisc_tree_reduce_backlog(), which, now that the child
is empty, invokes hfsc_qlen_notify() -> update_vf(cl, 0, 0) and turns
the class passive (cl_nactive is decremented up the hierarchy).

2. hfsc_dequeue() then calls update_vf(cl, qdisc_pkt_len(skb), cur_time)
to charge the dequeued bytes.

On the second call the class is already passive, but its child qdisc is
still empty, so update_vf() arms go_passive again:

if (cl->qdisc->q.qlen == 0 && cl->cl_flags & HFSC_FSC)
go_passive = 1;

The leaf is then skipped by the cl_nactive == 0 check inside the loop,
which does not clear go_passive, so the stale go_passive propagates to the
parent and decrements its cl_nactive a second time. A parent that still
has other active children is driven to cl_nactive == 0 and removed from
the vttree, even though those siblings are still backlogged. They are
never dequeued again and the qdisc stalls.

Fix this by only arming go_passive when the class is actually active, so an
already-passive class no longer triggers a second passive transition. The
byte accounting (cl->cl_total += len) still runs for every ancestor, so
dequeued bytes continue to be counted exactly once.

Affected products

VendorProductAffectedFixed
Linux Linux 5.10.241 – < 5.10.261, 5.15.190 – < 5.15.212, 6.1.138 – < 6.1.178, 6.6.90 – < 6.6.145, 6.12.28 – < 6.12.97, 5.4.297 – < 5.5, 6.14.6 – < 6.15, 6.15 5.10.261

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 7.1.5-1 —
Debian 13 linux 6.12.100-1 —
Debian 12 linux 6.1.180-1 —
ReleasePackageFixed inAdvisory
Ubuntu Nvidia-BlueField 24.04 LTS linux-bluefield 6.8.0-1033.38 —
Ubuntu Nvidia-BlueField 22.04 LTS linux-bluefield 5.15.0-1101.103 —
Ubuntu 26.04 LTS linux 7.0.0-38.38 USN-8887-1
Ubuntu 26.04 LTS linux-aws +1 7.0.0-1014.14 USN-8887-1
Ubuntu 26.04 LTS linux-azure 7.0.0-1017.17 USN-8888-1
Ubuntu 26.04 LTS linux-azure-fde 7.0.0-1016.16 USN-8888-1
Ubuntu 26.04 LTS linux-gke 7.0.0-1008.9 USN-8887-1
Ubuntu 26.04 LTS linux-ibm +1 7.0.0-1015.15 USN-8889-1, USN-8887-1
Ubuntu 26.04 LTS linux-nvidia 7.0.0-1025.26 USN-9043-1
Ubuntu 26.04 LTS linux-nvidia-bos 7.0.0-2022.23 USN-9003-1
Ubuntu 26.04 LTS linux-oracle 7.0.0-1013.13 USN-8887-1
Ubuntu 26.04 LTS linux-raspi 7.0.0-1023.23 USN-9021-1
Ubuntu 26.04 LTS linux-riscv +1 7.0.0-38.38.1 USN-8887-1
Ubuntu 24.04 LTS linux 6.8.0-147.147 USN-8917-1
Ubuntu 24.04 LTS linux-aws +1 6.8.0-1067.70 USN-9024-1, USN-8917-1
Ubuntu 24.04 LTS linux-aws-7.0 +1 7.0.0-1014.14~24.04.1 USN-8887-3, USN-8887-2
Ubuntu 24.04 LTS linux-azure-7.0 7.0.0-1017.17~24.04.1 USN-8888-2
Ubuntu 24.04 LTS linux-azure-fde 6.8.0-1069.76 USN-8918-1
Ubuntu 24.04 LTS linux-azure-fde-7.0 7.0.0-1016.16~24.04.1 USN-8888-2
Ubuntu 24.04 LTS linux-gcp +1 6.8.0-1071.79 USN-8918-1, USN-8917-1
Ubuntu 24.04 LTS linux-gke 6.8.0-1066.74 USN-8917-1
Ubuntu 24.04 LTS linux-gkeop 6.8.0-1052.56 USN-8917-1
Ubuntu 24.04 LTS linux-hwe-7.0 7.0.0-38.38~24.04.4 USN-8887-3
Ubuntu 24.04 LTS linux-ibm 6.8.0-1067.68 USN-8917-1
Ubuntu 24.04 LTS linux-lowlatency 6.8.0-147.147.1 USN-8917-1
Ubuntu 24.04 LTS linux-nvidia-7.0 7.0.0-1024.25~24.04.1 USN-9003-1
Ubuntu 24.04 LTS linux-nvidia-lowlatency 6.8.0-1067.70.1 USN-9040-1
Ubuntu 24.04 LTS linux-oracle 6.8.0-1064.67 USN-8917-1
Ubuntu 24.04 LTS linux-oracle-7.0 7.0.0-1013.13~24.04.1 USN-8887-3
Ubuntu 24.04 LTS linux-raspi 6.8.0-1068.72 USN-9025-1
Ubuntu 24.04 LTS linux-riscv +30 No fix yet —
Ubuntu 24.04 LTS linux-riscv-7.0 7.0.0-38.38.1~24.04.1 —
Ubuntu 24.04 LTS linux-vmware 6.8.0-1008.8 —
Ubuntu 22.04 LTS linux 5.15.0-198.208 USN-8875-1
Ubuntu 22.04 LTS linux-aws 5.15.0-1117.124 USN-8875-1
Ubuntu 22.04 LTS linux-aws-6.8 6.8.0-1069.74~22.04.1 USN-9024-1
Ubuntu 22.04 LTS linux-azure 5.15.0-1123.132 USN-8875-1
Ubuntu 22.04 LTS linux-azure-6.8 6.8.0-1073.82~22.04.1 USN-9026-1
Ubuntu 22.04 LTS linux-azure-fde 5.15.0-1122.131 USN-8876-1
Ubuntu 22.04 LTS linux-azure-fde-6.8 6.8.0-1071.78~22.04.1 USN-9026-1
Ubuntu 22.04 LTS linux-gcp 5.15.0-1118.128 USN-8877-1
Ubuntu 22.04 LTS linux-gcp-6.8 6.8.0-1073.81~22.04.1 USN-9024-1
Ubuntu 22.04 LTS linux-gke 5.15.0-1113.119 USN-8875-1
Ubuntu 22.04 LTS linux-gkeop 5.15.0-1100.108 USN-8875-1
Ubuntu 22.04 LTS linux-hwe-6.8 6.8.0-149.149~22.04.1 USN-9066-1
Ubuntu 22.04 LTS linux-ibm 5.15.0-1111.115 USN-8875-1
Ubuntu 22.04 LTS linux-ibm-6.8 6.8.0-1069.70~22.04.1 USN-9024-1
Ubuntu 22.04 LTS linux-intel-iotg 5.15.0-1112.118 USN-8875-1
Ubuntu 22.04 LTS linux-kvm 5.15.0-1109.114 USN-8875-1
Ubuntu 22.04 LTS linux-lowlatency 5.15.0-195.205 USN-8875-1
Ubuntu 22.04 LTS linux-lowlatency-hwe-6.8 6.8.0-149.149.1~22.04.1 USN-9024-1
Ubuntu 22.04 LTS linux-nvidia 5.15.0-1112.113 USN-8875-2
Ubuntu 22.04 LTS linux-nvidia-tegra 5.15.0-1070.72 USN-8963-1
Ubuntu 22.04 LTS linux-nvidia-tegra-igx 5.15.0-1059.59 USN-8963-1
Ubuntu 22.04 LTS linux-oracle 5.15.0-1114.120 USN-8875-1
Ubuntu 22.04 LTS linux-oracle-6.8 6.8.0-1067.71~22.04.1 USN-9025-1
Ubuntu 22.04 LTS linux-raspi 5.15.0-1113.116 USN-9029-1
Ubuntu 22.04 LTS linux-riscv +33 No fix yet —
Ubuntu 22.04 LTS linux-xilinx-zynqmp 5.15.0-1080.84 USN-8875-1
Show 14 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 6.8.0-2056.58 USN-9025-1
Ubuntu Pro Realtime 24.04 LTS linux-realtime 6.8.1-1062.63 USN-8917-1
Ubuntu Pro Realtime 24.04 LTS linux-realtime-6.14 +1 No fix yet —
Ubuntu Pro Realtime 22.04 LTS linux-intel-iot-realtime 5.15.0-1109.111 USN-8875-1
Ubuntu Pro Realtime 22.04 LTS linux-realtime 5.15.0-1116.125 USN-8875-1
Ubuntu Pro Realtime 22.04 LTS linux-realtime-6.8 6.8.1-1064.65~22.04.1 USN-9024-1
Ubuntu Pro FIPS-updates 24.04 LTS linux-aws-fips 6.8.0-1067.70+fips1 USN-8917-1
Ubuntu Pro FIPS-updates 24.04 LTS linux-fips 6.8.0-147.147+fips1 USN-8917-1
Ubuntu Pro FIPS-updates 24.04 LTS linux-gcp-fips +1 6.8.0-1071.79+fips1 USN-8918-1, USN-8917-1
Ubuntu Pro FIPS-updates 22.04 LTS linux-aws-fips 5.15.0-1117.124+fips1 USN-8875-1
Ubuntu Pro FIPS-updates 22.04 LTS linux-azure-fips 5.15.0-1123.132+fips1 USN-8875-1
Ubuntu Pro FIPS-updates 22.04 LTS linux-fips 5.15.0-198.208+fips1 USN-8875-1
Ubuntu Pro FIPS-updates 22.04 LTS linux-gcp-fips 5.15.0-1118.128+fips1 USN-8877-1
Ubuntu Pro FIPS-updates 20.04 LTS linux-fips +3 No fix yet —
Ubuntu Pro FIPS-updates 18.04 LTS linux-fips +3 No fix yet —
Ubuntu Pro FIPS-updates 16.04 LTS linux-fips No fix yet —
Ubuntu Pro 20.04 LTS linux +10 No fix yet —
Ubuntu Pro 20.04 LTS linux-aws-5.15 5.15.0-1117.124~20.04.1 USN-8875-1
Ubuntu Pro 20.04 LTS linux-azure-5.15 5.15.0-1123.132~20.04.1 USN-8875-1
Ubuntu Pro 20.04 LTS linux-azure-fde-5.15 5.15.0-1122.131~20.04.1 USN-8875-1
Ubuntu Pro 20.04 LTS linux-gcp-5.15 5.15.0-1118.128~20.04.1 USN-8878-1
Ubuntu Pro 20.04 LTS linux-hwe-5.15 5.15.0-198.208~20.04.1 USN-8875-1
Ubuntu Pro 20.04 LTS linux-ibm-5.15 +1 5.15.0-1111.115~20.04.1 USN-8875-1
Ubuntu Pro 20.04 LTS linux-intel-iotg-5.15 5.15.0-1112.118~20.04.1 USN-8875-1
Ubuntu Pro 20.04 LTS linux-lowlatency-hwe-5.15 5.15.0-195.205~20.04.1 USN-8875-1
Ubuntu Pro 20.04 LTS linux-nvidia-tegra-5.15 5.15.0-1070.72~20.04.1 USN-8963-1
Ubuntu Pro 20.04 LTS linux-oracle-5.15 5.15.0-1114.120~20.04.1 USN-8879-1
Ubuntu Pro 18.04 LTS linux +12 No fix yet —
Ubuntu Pro 16.04 LTS linux +7 No fix yet —
Ubuntu Pro 14.04 LTS linux-aws +2 No fix yet —
ReleasePackageFixed inAdvisory
SLES 15 SP7 kernel-64kb +7 6.4.0-150700.53.84.1 SUSE-SU-2026:4706-1
SLES 15 SP7 kernel-default-base 6.4.0-150700.53.84.1.150700.17.47.1 SUSE-SU-2026:4706-1
SLES 12 SP5 kernel-syms +2 4.12.14-122.333.2 SUSE-SU-2026:4687-1
Show 8 more (older releases, extended support, other products)
ReleasePackageFixed inAdvisory
SLES for SAP 16.0 kernel-64kb +8 6.12.0-160000.38.1 SUSE-SU-2026:23902-1
SLES for SAP 16.0 kernel-default-base 6.12.0-160000.38.1.160000.2.23 SUSE-SU-2026:23902-1
SLES 16.0 kernel-64kb +8 6.12.0-160000.38.1 SUSE-SU-2026:23902-1, SUSE-SU-2026:23897-1
SLES 16.0 kernel-default-base 6.12.0-160000.38.1.160000.2.23 SUSE-SU-2026:23902-1
SLE Micro 6.2 kernel-default-base 6.12.0-160000.38.1.160000.2.23 SUSE-SU-2026:23887-1
SLE Micro 6.2 kernel-rt +5 6.12.0-160000.38.1 SUSE-SU-2026:23887-1, SUSE-SU-2026:23881-1
SLE Micro 6.2 podman 5.4.2-160000.6.1 SUSE-SU-2026:24182-1
SLE Micro 6.1 kernel-default-base 6.4.0-159998.53.1.159998.21.38 SUSE-SU-2026:24181-1
SLE Micro 6.1 kernel-rt +4 6.4.0-159998.53.1 SUSE-SU-2026:24182-1, SUSE-SU-2026:24181-1
SLE Micro 6.0 kernel-default-base 6.4.0-159998.53.1.159998.21.38 SUSE-SU-2026:24315-1
SLE Micro 6.0 kernel-rt +4 6.4.0-159998.53.1 SUSE-SU-2026:24316-1, SUSE-SU-2026:24315-1
SLE Live Patching 15 SP7 kernel-default 6.4.0-150700.53.84.1 SUSE-SU-2026:4706-1
SLE Live Patching 15 SP7 kernel-livepatch-SLE15-SP7-RT_Update_21 1-150700.1.3.1 SUSE-SU-2026:4640-1
SLE Live Patching 15 SP7 kernel-livepatch-SLE15-SP7_Update_22 1-150700.15.3.1 SUSE-SU-2026:4706-1
SLE Live Patching 12 SP5 kernel-default 4.12.14-122.333.2 SUSE-SU-2026:4687-1
SLE Live Patching 12 SP5 kgraft-patch-SLE12-SP5_Update_88 1-8.3.3 SUSE-SU-2026:4687-1
SUSE Real Time Module 15 SP7 kernel-rt +2 6.4.0-150700.7.78.1 SUSE-SU-2026:4640-1
ReleasePackageFixed inAdvisory
openSUSE Leap 16.0 kernel-default-base 6.12.0-160000.38.1.160000.2.22 openSUSE-SU-2026:21910-1
openSUSE Leap 16.0 kernel-rt +11 6.12.0-160000.38.1 openSUSE-SU-2026:21910-1

Amazon Linux

ReleasePackageFixed inAdvisory
Amazon Linux 2023 kernel-livepatch-6.18.41-94.142 +2 1:1.0-0.amzn2023 ALAS2023-2026-2071, ALAS2023-2026-2058, ALAS2023-2026-2057
Amazon Linux 2023 perf +11 1:6.1.180-225.360.amzn2023 ALAS2023-2026-2058
Amazon Linux 2023 perf6.12 +11 1:6.12.100-125.179.amzn2023 ALAS2023-2026-2057
Amazon Linux 2023 perf6.18 +12 1:6.18.41-94.142.amzn2023 ALAS2023-2026-2071

Oracle Linux

ReleasePackageFixed inAdvisory
Oracle Linux 9 kernel-uek +34 6.12.0-206.104.3.3.el10uek ELSA-2026-500248
Oracle Linux 8 bpftool +18 5.15.0-324.217.5.2.el9uek ELSA-2026-500249

Advisories 42

References