CVE-2025-39979

net/mlx5: fs, fix UAF in flow counter release

Published Oct 15, 2025 CVSS 3.1 · 7.8 High EPSS < 1% KEV · Not listed
Description
In the Linux kernel, the following vulnerability has been resolved:

net/mlx5: fs, fix UAF in flow counter release

Fix a kernel trace [1] caused by releasing an HWS action of a local flow
counter in mlx5_cmd_hws_delete_fte(), where the HWS action refcount and
mutex were not initialized and the counter struct could already be freed
when deleting the rule.

Fix it by adding the missing initializations and adding refcount for the
local flow counter struct.

[1] Kernel log:
Call Trace:
<TASK>
dump_stack_lvl+0x34/0x48
mlx5_fs_put_hws_action.part.0.cold+0x21/0x94 [mlx5_core]
mlx5_fc_put_hws_action+0x96/0xad [mlx5_core]
mlx5_fs_destroy_fs_actions+0x8b/0x152 [mlx5_core]
mlx5_cmd_hws_delete_fte+0x5a/0xa0 [mlx5_core]
del_hw_fte+0x1ce/0x260 [mlx5_core]
mlx5_del_flow_rules+0x12d/0x240 [mlx5_core]
? ttwu_queue_wakelist+0xf4/0x110
mlx5_ib_destroy_flow+0x103/0x1b0 [mlx5_ib]
uverbs_free_flow+0x20/0x50 [ib_uverbs]
destroy_hw_idr_uobject+0x1b/0x50 [ib_uverbs]
uverbs_destroy_uobject+0x34/0x1a0 [ib_uverbs]
uobj_destroy+0x3c/0x80 [ib_uverbs]
ib_uverbs_run_method+0x23e/0x360 [ib_uverbs]
? uverbs_finalize_object+0x60/0x60 [ib_uverbs]
ib_uverbs_cmd_verbs+0x14f/0x2c0 [ib_uverbs]
? do_tty_write+0x1a9/0x270
? file_tty_write.constprop.0+0x98/0xc0
? new_sync_write+0xfc/0x190
ib_uverbs_ioctl+0xd7/0x160 [ib_uverbs]
__x64_sys_ioctl+0x87/0xc0
do_syscall_64+0x59/0x90

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Type Values Removed Values Added
Metrics cvssV3_1

{'score': 7.0, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H'}

cvssV3_1

{'score': 7.8, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'}

Type Values Removed Values Added
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Type Values Removed Values Added
First Time appeared Linux
Linux linux Kernel
Vendors & Products Linux
Linux linux Kernel
Type Values Removed Values Added
References
Metrics threat_severity

None

cvssV3_1

{'score': 7.0, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H'}

threat_severity

Moderate

Type Values Removed Values Added
Description In the Linux kernel, the following vulnerability has been resolved: net/mlx5: fs, fix UAF in flow counter release Fix a kernel trace [1] caused by releasing an HWS action of a local flow counter in mlx5_cmd_hws_delete_fte(), where the HWS action refcount and mutex were not initialized and the counter struct could already be freed when deleting the rule. Fix it by adding the missing initializations and adding refcount for the local flow counter struct. [1] Kernel log: Call Trace: <TASK> dump_stack_lvl+0x34/0x48 mlx5_fs_put_hws_action.part.0.cold+0x21/0x94 [mlx5_core] mlx5_fc_put_hws_action+0x96/0xad [mlx5_core] mlx5_fs_destroy_fs_actions+0x8b/0x152 [mlx5_core] mlx5_cmd_hws_delete_fte+0x5a/0xa0 [mlx5_core] del_hw_fte+0x1ce/0x260 [mlx5_core] mlx5_del_flow_rules+0x12d/0x240 [mlx5_core] ? ttwu_queue_wakelist+0xf4/0x110 mlx5_ib_destroy_flow+0x103/0x1b0 [mlx5_ib] uverbs_free_flow+0x20/0x50 [ib_uverbs] destroy_hw_idr_uobject+0x1b/0x50 [ib_uverbs] uverbs_destroy_uobject+0x34/0x1a0 [ib_uverbs] uobj_destroy+0x3c/0x80 [ib_uverbs] ib_uverbs_run_method+0x23e/0x360 [ib_uverbs] ? uverbs_finalize_object+0x60/0x60 [ib_uverbs] ib_uverbs_cmd_verbs+0x14f/0x2c0 [ib_uverbs] ? do_tty_write+0x1a9/0x270 ? file_tty_write.constprop.0+0x98/0xc0 ? new_sync_write+0xfc/0x190 ib_uverbs_ioctl+0xd7/0x160 [ib_uverbs] __x64_sys_ioctl+0x87/0xc0 do_syscall_64+0x59/0x90
Title net/mlx5: fs, fix UAF in flow counter release
References
Weaknesses

No weakness.

Sources

Status
PUBLISHED
Assigner
Linux
Published
Updated
Oct 15, 2026, 10:02 PM
Reserved
Apr 16, 2025, 7:20 AM
Status
Deferred
Published
Oct 15, 2025, 8:15 AM
Modified
Oct 19, 2026, 9:10 PM
Severity
Moderate
Public date
Oct 15, 2025, 12:00 AM