CVE-2026-98014

Received Received - Intake

Memory Corruption in Linux Kernel MLX5 Driver

Publication date: 2026-09-25

Last updated on: 2026-10-03

Assigner: kernel.org

Description

In the Linux kernel, the following vulnerability has been resolved: net/mlx5: E-Switch, prevent mc_list repopulation during vport disable In mlx5_esw_vport_disable(), move esw_apply_vport_rx_mode() ahead of esw_vport_change_handle_locked() so vport->allmulti_rule is NULL before the change handler observes it. During FW-fatal recovery the disable runs while dev->state == INTERNAL_ERROR. The promisc query inside esw_update_vport_rx_mode() fails and returns early, leaving vport->allmulti_rule intact, so esw_update_vport_mc_promisc() runs and adds MLX5_ACTION_ADD entries to vport->mc_list whose flow rules are then installed in the FDB by esw_add_mc_addr(). esw_destroy_legacy_table() tears down the FDB with those refs still held, corrupting the sub-tree and leaving dangling flow_rule pointers in vport->mc_list. Two-stage failure on `echo 1 > /sys/bus/pci/devices/<bdf>/reset`: refcount_t: underflow; use-after-free. tree_put_node+0xef/0x110 [mlx5_core] clean_tree+0x44/0xd0 [mlx5_core] (x5) mlx5_fs_core_cleanup+0x57/0x1c0 [mlx5_core] mlx5_unload+0x65/0xd0 [mlx5_core] ... mlx5_health_try_recover BUG: unable to handle page fault for address: 0000000003000055 down_write+0x1c/0x60 mlx5_del_flow_rules+0x33/0x1f0 [mlx5_core] esw_del_mc_addr+0x7b/0x170 [mlx5_core] esw_apply_vport_addr_list+0x56/0xf0 [mlx5_core] esw_vport_change_handle_locked+0x28b/0x310 [mlx5_core] mlx5_esw_vport_enable+0x270/0x4a0 [mlx5_core] ... mlx5_load ... mlx5_health_try_recover esw_apply_vport_rx_mode(false, false) clears vport->allmulti_rule via its local state machine even when the FW del fails. With the rule NULL the !IS_ERR_OR_NULL(allmulti_rule) gate in the change handler closes, no rules are installed during disable, and the reload starts with a clean mc_list.

CVSS Scores

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Meta Information

Published

2026-09-25

Last Modified

2026-10-03

Generated

2026-10-16

AI Q&A

2026-09-25

EPSS Evaluated

2026-10-14

NVD

CVE-2026-98014

EUVD

EUVD-2026-86667

Affected Vendors & Products

Vendor	Product	Version / Range
mlx	mlx5_core	*
mlx	mlx5	*

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-UNKNOWN

Attack-Flow Graph

Executive Summary

This vulnerability in the Linux kernel involves a use-after-free and underflow issue in the mlx5 driver during FW-fatal recovery. It occurs when vport->allmulti_rule is not properly cleared, leading to corrupted flow rules and dangling pointers in vport->mc_list during device reset.

Detection Guidance

This vulnerability is specific to the Linux kernel's mlx5 driver and involves memory corruption during PCI device reset. Detection requires checking kernel logs for errors related to mlx5_core, underflow warnings, or page faults during device reset operations. Monitor logs with: dmesg | grep mlx5_core or journalctl -k | grep mlx5.

Impact Analysis

This vulnerability can cause system crashes due to use-after-free errors and page faults. It may lead to kernel instability, data corruption, or denial of service during device recovery or reset operations.

Compliance Impact

This vulnerability is specific to the Linux kernel's mlx5 driver and involves memory corruption and use-after-free issues during network device recovery. It does not directly relate to data privacy, access controls, or encryption mechanisms typically addressed by GDPR or HIPAA. Compliance impact would be indirect if this flaw leads to system instability or crashes that disrupt data processing or storage systems subject to these regulations.

Mitigation Strategies

Apply the latest kernel updates from your distribution to ensure the fix is included. Avoid triggering PCI device resets (echo 1 > /sys/bus/pci/devices/<bdf>/reset) until patched. If resets are unavoidable, consider temporarily disabling affected mlx5 devices.

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