CVE-2026-23173
Unknown Unknown - Not Provided
NULL Pointer Dereference in Linux mlx5e TC Flow Deletion

Publication date: 2026-02-14

Last updated on: 2026-03-18

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: net/mlx5e: TC, delete flows only for existing peers When deleting TC steering flows, iterate only over actual devcom peers instead of assuming all possible ports exist. This avoids touching non-existent peers and ensures cleanup is limited to devices the driver is currently connected to. BUG: kernel NULL pointer dereference, address: 0000000000000008 #PF: supervisor write access in kernel mode #PF: error_code(0x0002) - not-present page PGD 133c8a067 P4D 0 Oops: Oops: 0002 [#1] SMP CPU: 19 UID: 0 PID: 2169 Comm: tc Not tainted 6.18.0+ #156 NONE Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014 RIP: 0010:mlx5e_tc_del_fdb_peers_flow+0xbe/0x200 [mlx5_core] Code: 00 00 a8 08 74 a8 49 8b 46 18 f6 c4 02 74 9f 4c 8d bf a0 12 00 00 4c 89 ff e8 0e e7 96 e1 49 8b 44 24 08 49 8b 0c 24 4c 89 ff <48> 89 41 08 48 89 08 49 89 2c 24 49 89 5c 24 08 e8 7d ce 96 e1 49 RSP: 0018:ff11000143867528 EFLAGS: 00010246 RAX: 0000000000000000 RBX: dead000000000122 RCX: 0000000000000000 RDX: ff11000143691580 RSI: ff110001026e5000 RDI: ff11000106f3d2a0 RBP: dead000000000100 R08: 00000000000003fd R09: 0000000000000002 R10: ff11000101c75690 R11: ff1100085faea178 R12: ff11000115f0ae78 R13: 0000000000000000 R14: ff11000115f0a800 R15: ff11000106f3d2a0 FS: 00007f35236bf740(0000) GS:ff110008dc809000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000008 CR3: 0000000157a01001 CR4: 0000000000373eb0 Call Trace: <TASK> mlx5e_tc_del_flow+0x46/0x270 [mlx5_core] mlx5e_flow_put+0x25/0x50 [mlx5_core] mlx5e_delete_flower+0x2a6/0x3e0 [mlx5_core] tc_setup_cb_reoffload+0x20/0x80 fl_reoffload+0x26f/0x2f0 [cls_flower] ? mlx5e_tc_reoffload_flows_work+0xc0/0xc0 [mlx5_core] ? mlx5e_tc_reoffload_flows_work+0xc0/0xc0 [mlx5_core] tcf_block_playback_offloads+0x9e/0x1c0 tcf_block_unbind+0x7b/0xd0 tcf_block_setup+0x186/0x1d0 tcf_block_offload_cmd.isra.0+0xef/0x130 tcf_block_offload_unbind+0x43/0x70 __tcf_block_put+0x85/0x160 ingress_destroy+0x32/0x110 [sch_ingress] __qdisc_destroy+0x44/0x100 qdisc_graft+0x22b/0x610 tc_get_qdisc+0x183/0x4d0 rtnetlink_rcv_msg+0x2d7/0x3d0 ? rtnl_calcit.isra.0+0x100/0x100 netlink_rcv_skb+0x53/0x100 netlink_unicast+0x249/0x320 ? __alloc_skb+0x102/0x1f0 netlink_sendmsg+0x1e3/0x420 __sock_sendmsg+0x38/0x60 ____sys_sendmsg+0x1ef/0x230 ? copy_msghdr_from_user+0x6c/0xa0 ___sys_sendmsg+0x7f/0xc0 ? ___sys_recvmsg+0x8a/0xc0 ? __sys_sendto+0x119/0x180 __sys_sendmsg+0x61/0xb0 do_syscall_64+0x55/0x640 entry_SYSCALL_64_after_hwframe+0x4b/0x53 RIP: 0033:0x7f35238bb764 Code: 15 b9 86 0c 00 f7 d8 64 89 02 b8 ff ff ff ff eb bf 0f 1f 44 00 00 f3 0f 1e fa 80 3d e5 08 0d 00 00 74 13 b8 2e 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 4c c3 0f 1f 00 55 48 89 e5 48 83 ec 20 89 55 RSP: 002b:00007ffed4c35638 EFLAGS: 00000202 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 000055a2efcc75e0 RCX: 00007f35238bb764 RDX: 0000000000000000 RSI: 00007ffed4c356a0 RDI: 0000000000000003 RBP: 00007ffed4c35710 R08: 0000000000000010 R09: 00007f3523984b20 R10: 0000000000000004 R11: 0000000000000202 R12: 00007ffed4c35790 R13: 000000006947df8f R14: 000055a2efcc75e0 R15: 00007ffed4c35780
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Meta Information
Published
2026-02-14
Last Modified
2026-03-18
Generated
2026-05-07
AI Q&A
2026-02-14
EPSS Evaluated
2026-05-05
NVD
CVE-2026-23173
EUVD
EUVD-2026-5866
Affected Vendors & Products
Showing 10 associated CPEs
Vendor Product Version / Range
linux linux_kernel 6.19
linux linux_kernel 6.19
linux linux_kernel 6.19
linux linux_kernel 6.19
linux linux_kernel 6.19
linux linux_kernel 6.19
linux linux_kernel From 6.7 (inc) to 6.12.69 (exc)
linux linux_kernel 6.19
linux linux_kernel From 6.13 (inc) to 6.18.9 (exc)
linux linux_kernel From 6.5 (inc) to 6.6.123 (exc)
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-476 The product dereferences a pointer that it expects to be valid but is NULL.
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?

This vulnerability exists in the Linux kernel's mlx5e network driver, specifically in the handling of TC (Traffic Control) steering flows. The issue occurs when deleting TC steering flows, where the code incorrectly assumes all possible ports exist instead of iterating only over actual device communication peers. This can lead to attempts to access non-existent peers, causing a kernel NULL pointer dereference and resulting in a kernel crash (Oops).


How can this vulnerability impact me? :

The impact of this vulnerability is a potential kernel crash due to a NULL pointer dereference when deleting TC steering flows in the mlx5e driver. This can cause system instability or denial of service as the kernel encounters an unrecoverable error.


How does this vulnerability affect compliance with common standards and regulations (like GDPR, HIPAA)?:

I don't know


How can this vulnerability be detected on my network or system? Can you suggest some commands?

This vulnerability manifests as a kernel NULL pointer dereference causing a kernel oops with messages related to mlx5e_tc_del_fdb_peers_flow and TC steering flows.

To detect this vulnerability on your system, you should monitor kernel logs for oops or panic messages referencing mlx5e_tc_del_fdb_peers_flow or mlx5_core modules.

Commands to check kernel logs include:

  • dmesg | grep -i mlx5e_tc_del_fdb_peers_flow
  • journalctl -k | grep -i mlx5e_tc_del_fdb_peers_flow
  • grep -i 'BUG: kernel NULL pointer dereference' /var/log/kern.log

Additionally, monitoring for crashes or errors related to the 'tc' command or traffic control flows involving mlx5e devices may help identify attempts to trigger this issue.


What immediate steps should I take to mitigate this vulnerability?

The vulnerability has been resolved by ensuring that TC steering flows are deleted only for existing device communication peers, avoiding touching non-existent peers.

Immediate mitigation steps include:

  • Update the Linux kernel to a version that includes the fix for this vulnerability.
  • Avoid using TC steering flows or deleting flows on mlx5e devices until the kernel is patched.
  • Monitor kernel logs for related errors and avoid running untrusted traffic control commands that may trigger the issue.

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