EUVD-2026-15307
GHSA-27rj-chmq-rh6r
CVSS VectorNVD
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Lifecycle Timeline
6DescriptionNVD
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: <TASK> ... __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 ... </TASK>
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.
AnalysisAI
Use-after-free in Linux kernel network traffic control subsystem allows local authenticated attackers to execute arbitrary code with high privileges when changing network queue pair configurations on lockless qdiscs (virtio-net confirmed affected). Race condition between qdisc_reset_all_tx_gt() and dequeue operations causes memory to be freed while still in use. …
Sign in for full analysis, threat intelligence, and remediation guidance.
RemediationAI
Within 24 hours: Identify all Linux systems running kernel versions 6.1.x (before 6.1.167), 6.6.x (before 6.6.130), 6.12.x (before 6.12.77), 6.18.x (before 6.18.17), 6.19.x (before 6.19.7), or earlier branches with lockless qdiscs enabled; prioritize production systems with virtio-net devices. Within 7 days: Deploy vendor-released kernel patches (6.1.167, 6.6.130, 6.12.77, 6.18.17, 6.19.7, or mainline 7.0-rc3 as applicable) to all affected systems via coordinated maintenance windows. …
Sign in for detailed remediation steps.
More from same product – last 7 days
Kernel availability loss in Ubuntu Linux 6.8, 6.17, and 7.0 can be triggered by any unprivileged local user via a defect
Kernel panic via NULL pointer dereference in Ubuntu Linux 6.8's AppArmor notification handler allows a locally authentic
NULL pointer dereference in Ubuntu Linux kernel versions 6.8, 6.17, and 7.0 allows a local unprivileged user to crash th
NULL pointer dereference in Ubuntu Linux kernel SAUCE patches (versions 6.8, 6.17, and 7.0) allows an unprivileged local
In the Linux kernel, the following vulnerability has been resolved: netfilter: arp_tables: fix IEEE1394 ARP payload par
Vendor StatusVendor
Debian
| Release | Status | Fixed Version | Urgency |
|---|---|---|---|
| bullseye | vulnerable | 5.10.223-1 | - |
| bullseye (security) | vulnerable | 5.10.251-1 | - |
| bookworm | vulnerable | 6.1.159-1 | - |
| bookworm (security) | vulnerable | 6.1.164-1 | - |
| trixie | vulnerable | 6.12.73-1 | - |
| trixie (security) | vulnerable | 6.12.74-2 | - |
| forky, sid | fixed | 6.19.8-1 | - |
| (unstable) | fixed | 6.19.8-1 | - |
Share
External POC / Exploit Code
Leaving vuln.today