UBUNTU-CVE-2026-74284: Medium severity ubuntu/linux-aws vulnerability

Q: Which systems are exposed to this issue?

The affected software list includes Ubuntu linux, linux-aws, linux-azure, linux-gcp, linux-oracle, linux-fips, linux-realtime, and linux-kvm kernels. The failure requires an HFSC hierarchy where a class has a child qdisc and sibling classes remain backlogged.

Q: What traffic condition triggers the scheduler failure?

It occurs when a child qdisc, such as codel or fq_codel, drops its last packets during dequeue. The same class is then made passive twice, which can incorrectly mark a parent with still-active sibling classes as inactive.

Q: How can an administrator recognize the impact?

A parent class can be removed from the virtual-time tree even though sibling classes still have queued packets. Those backlogged siblings are no longer dequeued, causing the qdisc to stall.

Published Aug 15, 2026

Updated

In the Linux kernel, the following vulnerability has been resolved: net/sched: schhfsc: Don't make class passive twice updatevf() is called from two places for the same class during a single dequeue when the class's child qdisc (e.g. codel/fqcodel) drops its last packets while dequeuing: 1. The child calls qdisctreereducebacklog(), which, now that the child is empty, invokes hfscqlennotify() -> updatevf(cl, 0, 0) and turns the class passive (clnactive is decremented up the hierarchy). 2. hfscdequeue() then calls updatevf(cl, qdiscpktlen(skb), curtime) to charge the dequeued bytes. On the second call the class is already passive, but its child qdisc is still empty, so updatevf() arms gopassive again: if (cl->qdisc->q.qlen == 0 && cl->clflags & HFSCFSC) gopassive = 1; The leaf is then skipped by the clnactive == 0 check inside the loop, which does not clear gopassive, so the stale gopassive propagates to the parent and decrements its clnactive a second time. A parent that still has other active children is driven to clnactive == 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 gopassive when the class is actually active, so an already-passive class no longer triggers a second passive transition. The byte accounting (cl->cltotal += len) still runs for every ancestor, so dequeued bytes continue to be counted exactly once.

Affected Software

240 affected componentsFixes available

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*

ubuntu/linux-azure*

ubuntu/linux-azure-4.15*

ubuntu/linux-azure-5.3*

ubuntu/linux-azure-5.4*

ubuntu/linux-azure-edge*

ubuntu/linux-gcp*

ubuntu/linux-gcp-4.15*

ubuntu/linux-gcp-5.3*

ubuntu/linux-gcp-5.4*

ubuntu/linux-gke-4.15*

ubuntu/linux-gke-5.4*

ubuntu/linux-gkeop-5.4*

ubuntu/linux-hwe*

ubuntu/linux-hwe-5.4*

ubuntu/linux-hwe-edge*

ubuntu/linux-ibm-5.4*

ubuntu/linux-kvm*

ubuntu/linux-oem*

ubuntu/linux-oracle*

ubuntu/linux-oracle-5.0*

ubuntu/linux-oracle-5.3*

ubuntu/linux-oracle-5.4*

ubuntu/linux-raspi-5.4*

ubuntu/linux-aws-fips*

ubuntu/linux-azure-fips*

ubuntu/linux-fips*

ubuntu/linux-gcp-fips*

ubuntu/linux*

ubuntu/linux-aws*

ubuntu/linux-aws-5.11*

ubuntu/linux-aws-5.13*

ubuntu/linux-aws-5.15<5.15.0-1117.124~20.04.1

5.15.0-1117.124~20.04.1

ubuntu/linux-aws-5.8*

ubuntu/linux-azure*

ubuntu/linux-azure-5.11*

ubuntu/linux-azure-5.13*

ubuntu/linux-azure-5.15<5.15.0-1123.132~20.04.1

5.15.0-1123.132~20.04.1

ubuntu/linux-azure-5.8*

ubuntu/linux-azure-fde*

ubuntu/linux-azure-fde-5.15<5.15.0-1122.131~20.04.1

5.15.0-1122.131~20.04.1

ubuntu/linux-bluefield*

ubuntu/linux-gcp*

ubuntu/linux-gcp-5.11*

ubuntu/linux-gcp-5.13*

ubuntu/linux-gcp-5.15<5.15.0-1118.128~20.04.1

5.15.0-1118.128~20.04.1

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<5.15.0-198.208~20.04.1

5.15.0-198.208~20.04.1

ubuntu/linux-hwe-5.8*

ubuntu/linux-ibm*

ubuntu/linux-ibm-5.15<5.15.0-1111.115~20.04.1

5.15.0-1111.115~20.04.1

ubuntu/linux-intel-5.13*

ubuntu/linux-intel-iotg-5.15<5.15.0-1112.118~20.04.1

5.15.0-1112.118~20.04.1

ubuntu/linux-iot*

ubuntu/linux-kvm*

ubuntu/linux-lowlatency-hwe-5.15<5.15.0-195.205~20.04.1

5.15.0-195.205~20.04.1

ubuntu/linux-nvidia-tegra-5.15*

ubuntu/linux-oem-5.10*

ubuntu/linux-oem-5.13*

ubuntu/linux-oem-5.6*

ubuntu/linux-oracle*

ubuntu/linux-oracle-5.11*

ubuntu/linux-oracle-5.13*

ubuntu/linux-oracle-5.15<5.15.0-1114.120~20.04.1

5.15.0-1114.120~20.04.1

ubuntu/linux-oracle-5.8*

ubuntu/linux-raspi*

ubuntu/linux-raspi2*

ubuntu/linux-riscv*

ubuntu/linux-riscv-5.11*

ubuntu/linux-riscv-5.15<5.15.0-1111.115~20.04.1

5.15.0-1111.115~20.04.1

ubuntu/linux-riscv-5.8*

ubuntu/linux-xilinx-zynqmp*

ubuntu/linux-aws-fips*

ubuntu/linux-azure-fips*

ubuntu/linux-fips*

ubuntu/linux-gcp-fips*

ubuntu/linux<5.15.0-198.208

5.15.0-198.208

ubuntu/linux-allwinner-5.19*

ubuntu/linux-aws<5.15.0-1117.124

5.15.0-1117.124

ubuntu/linux-aws-5.19*

ubuntu/linux-aws-6.2*

ubuntu/linux-aws-6.5*

ubuntu/linux-aws-6.8*

ubuntu/linux-azure<5.15.0-1123.132

5.15.0-1123.132

ubuntu/linux-azure-5.19*

ubuntu/linux-azure-6.2*

ubuntu/linux-azure-6.5*

ubuntu/linux-azure-6.8*

ubuntu/linux-azure-fde<5.15.0-1122.131

5.15.0-1122.131

ubuntu/linux-azure-fde-5.19*

ubuntu/linux-azure-fde-6.2*

ubuntu/linux-azure-fde-6.8*

ubuntu/linux-gcp<5.15.0-1118.128

5.15.0-1118.128

ubuntu/linux-gcp-5.19*

ubuntu/linux-gcp-6.2*

ubuntu/linux-gcp-6.5*

ubuntu/linux-gcp-6.8*

ubuntu/linux-gke<5.15.0-1113.119

5.15.0-1113.119

ubuntu/linux-gkeop<5.15.0-1100.108

5.15.0-1100.108

ubuntu/linux-hwe-5.19*

ubuntu/linux-hwe-6.2*

ubuntu/linux-hwe-6.5*

ubuntu/linux-ibm<5.15.0-1111.115

5.15.0-1111.115

ubuntu/linux-ibm-6.8*

ubuntu/linux-intel-iot-realtime*

ubuntu/linux-intel-iotg<5.15.0-1112.118

5.15.0-1112.118

ubuntu/linux-kvm<5.15.0-1109.114

5.15.0-1109.114

ubuntu/linux-lowlatency<5.15.0-195.205

5.15.0-195.205

ubuntu/linux-lowlatency-hwe-5.19*

ubuntu/linux-lowlatency-hwe-6.2*

ubuntu/linux-lowlatency-hwe-6.5*

ubuntu/linux-lowlatency-hwe-6.8*

ubuntu/linux-nvidia<5.15.0-1112.113

5.15.0-1112.113

ubuntu/linux-nvidia-6.2*

ubuntu/linux-nvidia-6.5*

ubuntu/linux-nvidia-6.8*

ubuntu/linux-nvidia-tegra*

ubuntu/linux-nvidia-tegra-igx*

ubuntu/linux-oem-5.17*

ubuntu/linux-oem-6.0*

ubuntu/linux-oem-6.1*

ubuntu/linux-oem-6.5*

ubuntu/linux-oracle<5.15.0-1114.120

5.15.0-1114.120

ubuntu/linux-oracle-6.5*

ubuntu/linux-oracle-6.8*

ubuntu/linux-raspi*

ubuntu/linux-realtime*

ubuntu/linux-riscv*

ubuntu/linux-riscv-5.19*

ubuntu/linux-riscv-6.5*

ubuntu/linux-riscv-6.8*

ubuntu/linux-starfive-5.19*

ubuntu/linux-starfive-6.2*

ubuntu/linux-starfive-6.5*

ubuntu/linux-xilinx-zynqmp<5.15.0-1080.84

5.15.0-1080.84

ubuntu/linux-bluefield<5.15.0-1101.103

5.15.0-1101.103

ubuntu/linux-intel-iot-realtime<5.15.0-1109.111

5.15.0-1109.111

ubuntu/linux-realtime<5.15.0-1116.125

5.15.0-1116.125

ubuntu/linux-realtime-6.8*

ubuntu/linux-aws-fips<5.15.0-1117.124+fips1

5.15.0-1117.124+fips1

ubuntu/linux-azure-fips<5.15.0-1123.132+fips1

5.15.0-1123.132+fips1

ubuntu/linux-fips<5.15.0-198.208+fips1

5.15.0-198.208+fips1

ubuntu/linux-gcp-fips<5.15.0-1118.128+fips1

5.15.0-1118.128+fips1

ubuntu/linux<6.8.0-147.147

6.8.0-147.147

ubuntu/linux-aws<6.8.0-1067.70

6.8.0-1067.70

ubuntu/linux-aws-6.14*

ubuntu/linux-aws-6.17*

ubuntu/linux-aws-7.0<7.0.0-1014.14~24.04.1

7.0.0-1014.14~24.04.1

ubuntu/linux-azure<6.8.0-1071.79

6.8.0-1071.79

ubuntu/linux-azure-6.11*

ubuntu/linux-azure-6.14*

ubuntu/linux-azure-6.17*

ubuntu/linux-azure-7.0<7.0.0-1017.17~24.04.1

7.0.0-1017.17~24.04.1

ubuntu/linux-azure-fde<6.8.0-1069.76

6.8.0-1069.76

ubuntu/linux-azure-fde-6.14*

ubuntu/linux-azure-fde-6.17*

ubuntu/linux-azure-fde-7.0<7.0.0-1016.16~24.04.1

7.0.0-1016.16~24.04.1

ubuntu/linux-azure-nvidia*

ubuntu/linux-azure-nvidia-6.14*

ubuntu/linux-gcp<6.8.0-1071.79

6.8.0-1071.79

ubuntu/linux-gcp-6.11*

ubuntu/linux-gcp-6.14*

ubuntu/linux-gcp-7.0<7.0.0-1014.14~24.04.1

7.0.0-1014.14~24.04.1

ubuntu/linux-gke<6.8.0-1066.74

6.8.0-1066.74

ubuntu/linux-gkeop<6.8.0-1052.56

6.8.0-1052.56

ubuntu/linux-hwe-6.11*

ubuntu/linux-hwe-6.14*

ubuntu/linux-hwe-6.17*

ubuntu/linux-hwe-7.0<7.0.0-38.38~24.04.4

7.0.0-38.38~24.04.4

ubuntu/linux-ibm<6.8.0-1067.68

6.8.0-1067.68

ubuntu/linux-lowlatency<6.8.0-147.147.1

6.8.0-147.147.1

ubuntu/linux-lowlatency-hwe-6.11*

ubuntu/linux-nvidia*

ubuntu/linux-nvidia-6.11*

ubuntu/linux-nvidia-6.17*

ubuntu/linux-nvidia-7.0*

ubuntu/linux-nvidia-lowlatency*

ubuntu/linux-nvidia-tegra*

ubuntu/linux-oem-6.11*

ubuntu/linux-oem-6.14*

ubuntu/linux-oem-6.17*

ubuntu/linux-oem-6.8*

ubuntu/linux-oracle<6.8.0-1064.67

6.8.0-1064.67

ubuntu/linux-oracle-6.14*

ubuntu/linux-oracle-6.17*

ubuntu/linux-oracle-7.0<7.0.0-1013.13~24.04.1

7.0.0-1013.13~24.04.1

ubuntu/linux-raspi*

ubuntu/linux-raspi-realtime*

ubuntu/linux-realtime*

ubuntu/linux-riscv*

ubuntu/linux-riscv-6.14*

ubuntu/linux-riscv-6.17*

ubuntu/linux-riscv-7.0<7.0.0-38.38.1~24.04.1

7.0.0-38.38.1~24.04.1

ubuntu/linux-xilinx*

ubuntu/linux-bluefield<6.8.0-1033.38

6.8.0-1033.38

ubuntu/linux-raspi-realtime*

ubuntu/linux-realtime<6.8.1-1062.63

6.8.1-1062.63

ubuntu/linux-realtime-6.14*

ubuntu/linux-realtime-6.17*

ubuntu/linux-aws-fips<6.8.0-1067.70+fips1

6.8.0-1067.70+fips1

ubuntu/linux-azure-fips<6.8.0-1071.79+fips1

6.8.0-1071.79+fips1

ubuntu/linux-fips<6.8.0-147.147+fips1

6.8.0-147.147+fips1

ubuntu/linux-gcp-fips<6.8.0-1071.79+fips1

6.8.0-1071.79+fips1

ubuntu/linux<7.0.0-38.38

7.0.0-38.38

ubuntu/linux-aws<7.0.0-1014.14

7.0.0-1014.14

ubuntu/linux-azure<7.0.0-1017.17

7.0.0-1017.17

ubuntu/linux-azure-fde<7.0.0-1016.16

7.0.0-1016.16

ubuntu/linux-gcp<7.0.0-1014.14

7.0.0-1014.14

ubuntu/linux-gke<7.0.0-1008.9

7.0.0-1008.9

ubuntu/linux-ibm<7.0.0-1015.15

7.0.0-1015.15

ubuntu/linux-nvidia*

ubuntu/linux-nvidia-bos*

ubuntu/linux-oem-7.0<7.0.0-1015.15

7.0.0-1015.15

ubuntu/linux-oracle<7.0.0-1013.13

7.0.0-1013.13

ubuntu/linux-raspi*

ubuntu/linux-realtime<7.0.0-38.38.1

7.0.0-38.38.1

ubuntu/linux-riscv<7.0.0-38.38.1

7.0.0-38.38.1

Remediation

Recommended actions to resolve this vulnerability, in priority order.

Upgrade
Upgrade ubuntu/linux-aws-5.15 to a version that resolves this vulnerability.
Fixed in 5.15.0-1117.124~20.04.1
Upgrade
Upgrade ubuntu/linux-azure-5.15 to a version that resolves this vulnerability.
Fixed in 5.15.0-1123.132~20.04.1
Upgrade
Upgrade ubuntu/linux-azure-fde-5.15 to a version that resolves this vulnerability.
Fixed in 5.15.0-1122.131~20.04.1
Upgrade
Upgrade ubuntu/linux-gcp-5.15 to a version that resolves this vulnerability.
Fixed in 5.15.0-1118.128~20.04.1
Upgrade
Upgrade ubuntu/linux-hwe-5.15 to a version that resolves this vulnerability.
Fixed in 5.15.0-198.208~20.04.1
Upgrade
Upgrade ubuntu/linux-ibm-5.15 to a version that resolves this vulnerability.
Fixed in 5.15.0-1111.115~20.04.1
Upgrade
Upgrade ubuntu/linux-intel-iotg-5.15 to a version that resolves this vulnerability.
Fixed in 5.15.0-1112.118~20.04.1
Upgrade
Upgrade ubuntu/linux-lowlatency-hwe-5.15 to a version that resolves this vulnerability.
Fixed in 5.15.0-195.205~20.04.1
Upgrade
Upgrade ubuntu/linux-oracle-5.15 to a version that resolves this vulnerability.
Fixed in 5.15.0-1114.120~20.04.1
Upgrade
Upgrade ubuntu/linux-riscv-5.15 to a version that resolves this vulnerability.
Fixed in 5.15.0-1111.115~20.04.1
Upgrade
Upgrade ubuntu/linux to a version that resolves this vulnerability.
Fixed in 5.15.0-198.208
Upgrade
Upgrade ubuntu/linux-aws to a version that resolves this vulnerability.
Fixed in 5.15.0-1117.124
Upgrade
Upgrade ubuntu/linux-azure to a version that resolves this vulnerability.
Fixed in 5.15.0-1123.132
Upgrade
Upgrade ubuntu/linux-azure-fde to a version that resolves this vulnerability.
Fixed in 5.15.0-1122.131
Upgrade
Upgrade ubuntu/linux-gcp to a version that resolves this vulnerability.
Fixed in 5.15.0-1118.128
Upgrade
Upgrade ubuntu/linux-gke to a version that resolves this vulnerability.
Fixed in 5.15.0-1113.119
Upgrade
Upgrade ubuntu/linux-gkeop to a version that resolves this vulnerability.
Fixed in 5.15.0-1100.108
Upgrade
Upgrade ubuntu/linux-ibm to a version that resolves this vulnerability.
Fixed in 5.15.0-1111.115
Upgrade
Upgrade ubuntu/linux-intel-iotg to a version that resolves this vulnerability.
Fixed in 5.15.0-1112.118
Upgrade
Upgrade ubuntu/linux-kvm to a version that resolves this vulnerability.
Fixed in 5.15.0-1109.114
Upgrade
Upgrade ubuntu/linux-lowlatency to a version that resolves this vulnerability.
Fixed in 5.15.0-195.205
Upgrade
Upgrade ubuntu/linux-nvidia to a version that resolves this vulnerability.
Fixed in 5.15.0-1112.113
Upgrade
Upgrade ubuntu/linux-oracle to a version that resolves this vulnerability.
Fixed in 5.15.0-1114.120
Upgrade
Upgrade ubuntu/linux-xilinx-zynqmp to a version that resolves this vulnerability.
Fixed in 5.15.0-1080.84
Upgrade
Upgrade ubuntu/linux-bluefield to a version that resolves this vulnerability.
Fixed in 5.15.0-1101.103
Upgrade
Upgrade ubuntu/linux-intel-iot-realtime to a version that resolves this vulnerability.
Fixed in 5.15.0-1109.111
Upgrade
Upgrade ubuntu/linux-realtime to a version that resolves this vulnerability.
Fixed in 5.15.0-1116.125
Upgrade
Upgrade ubuntu/linux-aws-fips to a version that resolves this vulnerability.
Fixed in 5.15.0-1117.124+fips1
Upgrade
Upgrade ubuntu/linux-azure-fips to a version that resolves this vulnerability.
Fixed in 5.15.0-1123.132+fips1
Upgrade
Upgrade ubuntu/linux-fips to a version that resolves this vulnerability.
Fixed in 5.15.0-198.208+fips1
Upgrade
Upgrade ubuntu/linux-gcp-fips to a version that resolves this vulnerability.
Fixed in 5.15.0-1118.128+fips1
Upgrade
Upgrade ubuntu/linux to a version that resolves this vulnerability.
Fixed in 6.8.0-147.147
Upgrade
Upgrade ubuntu/linux-aws to a version that resolves this vulnerability.
Fixed in 6.8.0-1067.70
Upgrade
Upgrade ubuntu/linux-aws-7.0 to a version that resolves this vulnerability.
Fixed in 7.0.0-1014.14~24.04.1
Upgrade
Upgrade ubuntu/linux-azure to a version that resolves this vulnerability.
Fixed in 6.8.0-1071.79
Upgrade
Upgrade ubuntu/linux-azure-7.0 to a version that resolves this vulnerability.
Fixed in 7.0.0-1017.17~24.04.1
Upgrade
Upgrade ubuntu/linux-azure-fde to a version that resolves this vulnerability.
Fixed in 6.8.0-1069.76
Upgrade
Upgrade ubuntu/linux-azure-fde-7.0 to a version that resolves this vulnerability.
Fixed in 7.0.0-1016.16~24.04.1
Upgrade
Upgrade ubuntu/linux-gcp to a version that resolves this vulnerability.
Fixed in 6.8.0-1071.79
Upgrade
Upgrade ubuntu/linux-gcp-7.0 to a version that resolves this vulnerability.
Fixed in 7.0.0-1014.14~24.04.1
Upgrade
Upgrade ubuntu/linux-gke to a version that resolves this vulnerability.
Fixed in 6.8.0-1066.74
Upgrade
Upgrade ubuntu/linux-gkeop to a version that resolves this vulnerability.
Fixed in 6.8.0-1052.56
Upgrade
Upgrade ubuntu/linux-hwe-7.0 to a version that resolves this vulnerability.
Fixed in 7.0.0-38.38~24.04.4
Upgrade
Upgrade ubuntu/linux-ibm to a version that resolves this vulnerability.
Fixed in 6.8.0-1067.68
Upgrade
Upgrade ubuntu/linux-lowlatency to a version that resolves this vulnerability.
Fixed in 6.8.0-147.147.1
Upgrade
Upgrade ubuntu/linux-oracle to a version that resolves this vulnerability.
Fixed in 6.8.0-1064.67
Upgrade
Upgrade ubuntu/linux-oracle-7.0 to a version that resolves this vulnerability.
Fixed in 7.0.0-1013.13~24.04.1
Upgrade
Upgrade ubuntu/linux-riscv-7.0 to a version that resolves this vulnerability.
Fixed in 7.0.0-38.38.1~24.04.1
Upgrade
Upgrade ubuntu/linux-bluefield to a version that resolves this vulnerability.
Fixed in 6.8.0-1033.38
Upgrade
Upgrade ubuntu/linux-realtime to a version that resolves this vulnerability.
Fixed in 6.8.1-1062.63
Upgrade
Upgrade ubuntu/linux-aws-fips to a version that resolves this vulnerability.
Fixed in 6.8.0-1067.70+fips1
Upgrade
Upgrade ubuntu/linux-azure-fips to a version that resolves this vulnerability.
Fixed in 6.8.0-1071.79+fips1
Upgrade
Upgrade ubuntu/linux-fips to a version that resolves this vulnerability.
Fixed in 6.8.0-147.147+fips1
Upgrade
Upgrade ubuntu/linux-gcp-fips to a version that resolves this vulnerability.
Fixed in 6.8.0-1071.79+fips1
Upgrade
Upgrade ubuntu/linux to a version that resolves this vulnerability.
Fixed in 7.0.0-38.38
Upgrade
Upgrade ubuntu/linux-aws to a version that resolves this vulnerability.
Fixed in 7.0.0-1014.14
Upgrade
Upgrade ubuntu/linux-azure to a version that resolves this vulnerability.
Fixed in 7.0.0-1017.17
Upgrade
Upgrade ubuntu/linux-azure-fde to a version that resolves this vulnerability.
Fixed in 7.0.0-1016.16
Upgrade
Upgrade ubuntu/linux-gcp to a version that resolves this vulnerability.
Fixed in 7.0.0-1014.14
Upgrade
Upgrade ubuntu/linux-gke to a version that resolves this vulnerability.
Fixed in 7.0.0-1008.9
Upgrade
Upgrade ubuntu/linux-ibm to a version that resolves this vulnerability.
Fixed in 7.0.0-1015.15
Upgrade
Upgrade ubuntu/linux-oem-7.0 to a version that resolves this vulnerability.
Fixed in 7.0.0-1015.15
Upgrade
Upgrade ubuntu/linux-oracle to a version that resolves this vulnerability.
Fixed in 7.0.0-1013.13
Upgrade
Upgrade ubuntu/linux-realtime to a version that resolves this vulnerability.
Fixed in 7.0.0-38.38.1
Upgrade
Upgrade ubuntu/linux-riscv to a version that resolves this vulnerability.
Fixed in 7.0.0-38.38.1

Event History

Aug 15, 2026

CVE Published

via OSV·06:22 AM

Data Sourced

via OSV·06:22 AM

DescriptionSeverityAffected Software

Frequently Asked Questions

Which systems are exposed to this issue?

The affected software list includes Ubuntu linux, linux-aws, linux-azure, linux-gcp, linux-oracle, linux-fips, linux-realtime, and linux-kvm kernels. The failure requires an HFSC hierarchy where a class has a child qdisc and sibling classes remain backlogged.

What traffic condition triggers the scheduler failure?

It occurs when a child qdisc, such as codel or fq_codel, drops its last packets during dequeue. The same class is then made passive twice, which can incorrectly mark a parent with still-active sibling classes as inactive.

How can an administrator recognize the impact?

A parent class can be removed from the virtual-time tree even though sibling classes still have queued packets. Those backlogged siblings are no longer dequeued, causing the qdisc to stall.

UBUNTU-CVE-2026-74284: Medium severity ubuntu/linux-aws vulnerability

Affected Software

Remediation

Event History

Frequently Asked Questions

Which systems are exposed to this issue?

What traffic condition triggers the scheduler failure?

How can an administrator recognize the impact?

Company

Resources

Contact