CVE-2023-54236
NoneCVSS
—
EPSS
0.2%
Published
Dec 30, 2025
CISA due date
—
Cloudanix analysis
A network handling feature inside the operating system could print extra warning messages when moving data across certain backup connections.
- Exploitation
- Other
- Attacker needs
- None
- Complexity
- Theoretical
- Impact
- Other
- Component
- OS kernel
- Class
- Other
- Remediation
- Patch
- Effort
- Low
- Patch risk
- None
What it actually does
The failover txq initializes to 16 queues but netdev_core_pick_tx can select a higher index returned from an active primary device with more queues, emitting a warning backtrace during packet transmission.
Why it matters to the business
Produces noisy kernel warnings on virtualized or bonded network setups using failover with high-queue primary devices, increasing log volume and operational noise without causing outages or data loss.
How an attack unfolds
An attacker sends UDP or TCP traffic through the failover device while the primary interface is up and has more than 16 TX queues; the kernel path in __dev_queue_xmit triggers the warning via netdev_core_pick_tx but performs no further malicious action.
How to fix it
Update the Linux kernel to the fixed commit 105cc268328231d5c2bfcbd03f265cec444a3492 or later stable releases that cap the failover txq count to match the primary device.
How to confirm the fix worked
Confirm the running kernel contains commit 105cc268328231d5c2bfcbd03f265cec444a3492 and verify that no 'selects TX queue' warnings appear when transmitting through failover devices backed by high-queue primaries.
Typical attack path
- Establish network connectivity via failover device with primary interface active
- Transmit packets that invoke ip_finish_output and udp_sendmsg paths
- Trigger netdev_core_pick_tx to request queue index > 16
- Observe warning in kernel log without gaining code execution or privileges
How to detect it
Search kernel logs and dmesg output for the string 'selects TX queue' combined with 'real number of TX queues is 16'; correlate with processes performing UDP or TCP sends on failover interfaces.
What your security team should do
- Apply the referenced kernel commit or distribution update containing the fix within normal patch cycles
- Monitor kernel logs for the specific TX queue selection warning string as a temporary detection measure
- Prioritize updates on systems that rely on net_failover bonding in virtualized environments
The record
In the Linux kernel, the following vulnerability has been resolved: net/net_failover: fix txq exceeding warning The failover txq is inited as 16 queues. when a packet is transmitted from the failover device firstly, the failover device will select the queue which is returned from the primary device if the primary device is UP and running. If the primary device txq is bigger than the default 16, it can lead to the following warning: eth0 selects TX queue 18, but real number of TX queues is 16 The warning backtrace is: [ 32.146376] CPU: 18 PID: 9134 Comm: chronyd Tainted: G E 6.2.8-1.el7.centos.x86_64 #1 [ 32.147175] Hardware name: Red Hat KVM, BIOS 1.10.2-3.el7_4.1 04/01/2014 [ 32.147730] Call Trace: [ 32.147971] <TASK> [ 32.148183] dump_stack_lvl+0x48/0x70 [ 32.148514] dump_stack+0x10/0x20 [ 32.148820] netdev_core_pick_tx+0xb1/0xe0 [ 32.149180] __dev_queue_xmit+0x529/0xcf0 [ 32.149533] ? __check_object_size.part.0+0x21c/0x2c0 [ 32.149967] ip_finish_output2+0x278/0x560 [ 32.150327] __ip_finish_output+0x1fe/0x2f0 [ 32.150690] ip_finish_output+0x2a/0xd0 [ 32.151032] ip_output+0x7a/0x110 [ 32.151337] ? __pfx_ip_finish_output+0x10/0x10 [ 32.151733] ip_local_out+0x5e/0x70 [ 32.152054] ip_send_skb+0x19/0x50 [ 32.152366] udp_send_skb.isra.0+0x163/0x3a0 [ 32.152736] udp_sendmsg+0xba8/0xec0 [ 32.153060] ? __folio_memcg_unlock+0x25/0x60 [ 32.153445] ? __pfx_ip_generic_getfrag+0x10/0x10 [ 32.153854] ? sock_has_perm+0x85/0xa0 [ 32.154190] inet_sendmsg+0x6d/0x80 [ 32.154508] ? inet_sendmsg+0x6d/0x80 [ 32.154838] sock_sendmsg+0x62/0x70 [ 32.155152] ____sys_sendmsg+0x134/0x290 [ 32.155499] ___sys_sendmsg+0x81/0xc0 [ 32.155828] ? _get_random_bytes.part.0+0x79/0x1a0 [ 32.156240] ? ip4_datagram_release_cb+0x5f/0x1e0 [ 32.156649] ? get_random_u16+0x69/0xf0 [ 32.156989] ? __fget_light+0xcf/0x110 [ 32.157326] __sys_sendmmsg+0xc4/0x210 [ 32.157657] ? __sys_connect+0xb7/0xe0 [ 32.157995] ? __audit_syscall_entry+0xce/0x140 [ 32.158388] ? syscall_trace_enter.isra.0+0x12c/0x1a0 [ 32.158820] __x64_sys_sendmmsg+0x24/0x30 [ 32.159171] do_syscall_64+0x38/0x90 [ 32.159493] entry_SYSCALL_64_after_hwframe+0x72/0xdc Fix that by reducing txq number as the non-existent primary-dev does.
Affected packages
| Ecosystem | Package | Introduced | Fixed |
|---|---|---|---|
| Linux | Kernel | 4.18.0 | 5.4.240 |
| SUSE:Linux Enterprise High Availability Extension 15 SP4 | kernel-default | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-ESPOS | kernel-64kb | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-ESPOS | kernel-default | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-ESPOS | kernel-default-base | 0 | 5.14.21-150400.24.194.1.150400.24.98.3 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-ESPOS | kernel-docs | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-ESPOS | kernel-obs-build | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-ESPOS | kernel-source | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-ESPOS | kernel-syms | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-LTSS | kernel-64kb | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-LTSS | kernel-default | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-LTSS | kernel-default-base | 0 | 5.14.21-150400.24.194.1.150400.24.98.3 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-LTSS | kernel-docs | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-LTSS | kernel-obs-build | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-LTSS | kernel-source | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-LTSS | kernel-syms | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise Live Patching 15 SP4 | kernel-default | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise Live Patching 15 SP4 | kernel-livepatch-SLE15-SP4_Update_48 | 0 | 1-150400.9.7.1 |
| SUSE:Linux Enterprise Micro 5.3 | kernel-default | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise Micro 5.3 | kernel-default-base | 0 | 5.14.21-150400.24.194.1.150400.24.98.3 |
| SUSE:Linux Enterprise Micro 5.3 | kernel-rt | 0 | 5.14.21-150400.15.142.1 |
| SUSE:Linux Enterprise Micro 5.3 | kernel-source-rt | 0 | 5.14.21-150400.15.142.1 |
| SUSE:Linux Enterprise Micro 5.4 | kernel-default | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise Micro 5.4 | kernel-default-base | 0 | 5.14.21-150400.24.194.1.150400.24.98.3 |
| SUSE:Linux Enterprise Micro 5.4 | kernel-rt | 0 | 5.14.21-150400.15.142.1 |
| SUSE:Linux Enterprise Micro 5.4 | kernel-source-rt | 0 | 5.14.21-150400.15.142.1 |
| SUSE:Linux Enterprise Micro 5.5 | kernel-rt | 0 | 5.14.21-150500.13.118.1 |
| SUSE:Linux Enterprise Micro 5.5 | kernel-source-rt | 0 | 5.14.21-150500.13.118.1 |
| SUSE:Linux Enterprise Server 15 SP4-LTSS | kernel-64kb | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise Server 15 SP4-LTSS | kernel-default | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise Server 15 SP4-LTSS | kernel-default-base | 0 | 5.14.21-150400.24.194.1.150400.24.98.3 |
| SUSE:Linux Enterprise Server 15 SP4-LTSS | kernel-docs | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise Server 15 SP4-LTSS | kernel-obs-build | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise Server 15 SP4-LTSS | kernel-source | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise Server 15 SP4-LTSS | kernel-syms | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise Server 15 SP4-LTSS | kernel-zfcpdump | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise Server for SAP Applications 15 SP4 | kernel-default | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise Server for SAP Applications 15 SP4 | kernel-default-base | 0 | 5.14.21-150400.24.194.1.150400.24.98.3 |
| SUSE:Linux Enterprise Server for SAP Applications 15 SP4 | kernel-docs | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise Server for SAP Applications 15 SP4 | kernel-obs-build | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise Server for SAP Applications 15 SP4 | kernel-source | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise Server for SAP Applications 15 SP4 | kernel-syms | 0 | 5.14.21-150400.24.194.1 |
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