🛡️ UBUNTU-CVE-2026-23340
⚪ Unknown ✅ No Known Exploit OSV
N/A
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

In the Linux kernel, the following vulnerability has been resolved: net: sched: avoid qdisc_reset_all_tx_gt() vs dequeue race for lockless qdiscs When shrinking the number of real tx queues, netif_set_real_num_tx_queues() calls qdisc_reset_all_tx_gt() to flush qdiscs for queues which will no longer be used. qdisc_reset_all_tx_gt() currently serializes qdisc_reset() with qdisc_lock(). However, for lockless qdiscs, the dequeue path is serialized by qdisc_run_begin/end() using qdisc->seqlock instead, so qdisc_reset() can run concurrently with __qdisc_run() and free skbs while they are still being dequeued, leading to UAF. This can easily be reproduced on e.g. virtio-net by imposing heavy traffic while frequently changing the number of queue pairs: iperf3 -ub0 -c $peer -t 0 & while :; do ethtool -L eth0 combined 1 ethtool -L eth0 combined 2 done With KASAN enabled, this leads to reports like: BUG: KASAN: slab-use-after-free in __qdisc_run+0x133f/0x1760 ... Call Trace: ... __qdisc_run+0x133f/0x1760 __dev_queue_xmit+0x248f/0x3550 ip_finish_output2+0xa42/0x2110 ip_output+0x1a7/0x410 ip_send_skb+0x2e6/0x480 udp_send_skb+0xb0a/0x1590 udp_sendmsg+0x13c9/0x1fc0 ... Allocated by task 1270 on cpu 5 at 44.558414s: ... alloc_skb_with_frags+0x84/0x7c0 sock_alloc_send_pskb+0x69a/0x830 __ip_append_data+0x1b86/0x48c0 ip_make_skb+0x1e8/0x2b0 udp_sendmsg+0x13a6/0x1fc0 ... Freed by task 1306 on cpu 3 at 44.558445s: ... kmem_cache_free+0x117/0x5e0 pfifo_fast_reset+0x14d/0x580 qdisc_reset+0x9e/0x5f0 netif_set_real_num_tx_queues+0x303/0x840 virtnet_set_channels+0x1bf/0x260 [virtio_net] ethnl_set_channels+0x684/0xae0 ethnl_default_set_doit+0x31a/0x890 ... Serialize qdisc_reset_all_tx_gt() against the lockless dequeue path by taking qdisc->seqlock for TCQ_F_NOLOCK qdiscs, matching the serialization model already used by dev_reset_queue(). Additionally clear QDISC_STATE_NON_EMPTY after reset so the qdisc state reflects an empty queue, avoiding needless re-scheduling.

Details

Severity Unknown
CVSS Score N/A
CVSS Vector CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CWE N/A
Public Exploit ✅ No
Source OSV
Published 2026-03-25
Updated 2026-06-09
Modified 2026-06-08
Fix URL N/A

Affected Packages

Software From version Fixed in
linux
linux-allwinner-5.19
linux-aws
linux-aws-5.0
linux-aws-5.11
linux-aws-5.13
linux-aws-5.15
linux-aws-5.19
linux-aws-5.3
linux-aws-5.4
linux-aws-5.8
linux-aws-6.14
linux-aws-6.17
linux-aws-6.2
linux-aws-6.5
linux-aws-6.8
linux-aws-fips
linux-azure
linux-azure-5.11
linux-azure-5.13
linux-azure-5.15
linux-azure-5.19
linux-azure-5.3
linux-azure-5.4
linux-azure-5.8
linux-azure-6.11
linux-azure-6.14
linux-azure-6.17
linux-azure-6.2
linux-azure-6.5
linux-azure-6.8
linux-azure-edge
linux-azure-fde
linux-azure-fde-5.19
linux-azure-fde-6.14
linux-azure-fde-6.17
linux-azure-fde-6.2
linux-azure-fde-6.8
linux-azure-fips
linux-azure-nvidia
linux-azure-nvidia-6.14
linux-bluefield
linux-fips
linux-gcp
linux-gcp-5.11
linux-gcp-5.13
linux-gcp-5.15
linux-gcp-5.19
linux-gcp-5.3
linux-gcp-5.4
linux-gcp-5.8
linux-gcp-6.11
linux-gcp-6.14
linux-gcp-6.17
linux-gcp-6.2
linux-gcp-6.5
linux-gcp-6.8
linux-gcp-fips
linux-gke
linux-gke-4.15
linux-gke-5.15
linux-gke-5.4
linux-gkeop
linux-gkeop-5.15
linux-gkeop-5.4
linux-hwe
linux-hwe-5.11
linux-hwe-5.13
linux-hwe-5.15
linux-hwe-5.19
linux-hwe-5.4
linux-hwe-5.8
linux-hwe-6.11
linux-hwe-6.14
linux-hwe-6.17
linux-hwe-6.2
linux-hwe-6.5
linux-hwe-6.8
linux-hwe-edge
linux-ibm
linux-ibm-5.15
linux-ibm-5.4
linux-ibm-6.8
linux-intel-5.13
linux-intel-iot-realtime
linux-intel-iotg
linux-intel-iotg-5.15
linux-iot
linux-kvm
linux-lowlatency
linux-lowlatency-hwe-5.15
linux-lowlatency-hwe-5.19
linux-lowlatency-hwe-6.11
linux-lowlatency-hwe-6.2
linux-lowlatency-hwe-6.5
linux-lowlatency-hwe-6.8
linux-nvidia
linux-nvidia-6.11
linux-nvidia-6.17
linux-nvidia-6.2
linux-nvidia-6.5
linux-nvidia-6.8
linux-nvidia-lowlatency
linux-nvidia-tegra
linux-nvidia-tegra-5.15
linux-nvidia-tegra-igx
linux-oem
linux-oem-5.10
linux-oem-5.13
linux-oem-5.14
linux-oem-5.17
linux-oem-5.6
linux-oem-6.0
linux-oem-6.1
linux-oem-6.11
linux-oem-6.14
linux-oem-6.17
linux-oem-6.5
linux-oem-6.8
linux-oracle
linux-oracle-5.0
linux-oracle-5.11
linux-oracle-5.13
linux-oracle-5.15
linux-oracle-5.3
linux-oracle-5.4
linux-oracle-5.8
linux-oracle-6.14
linux-oracle-6.17
linux-oracle-6.5
linux-oracle-6.8
linux-raspi
linux-raspi-5.4
linux-raspi-realtime
linux-raspi2
linux-realtime
linux-realtime-6.14
linux-realtime-6.17
linux-realtime-6.8
linux-riscv
linux-riscv-5.11
linux-riscv-5.15
linux-riscv-5.19
linux-riscv-5.8
linux-riscv-6.14
linux-riscv-6.17
linux-riscv-6.5
linux-riscv-6.8
linux-starfive-5.19
linux-starfive-6.2
linux-starfive-6.5
linux-xilinx
linux-xilinx-zynqmp

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