CVE-2025-39979

CVE-2025-39979 is a security vulnerability that is still awaiting full analysis and scoring. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low.

Key facts

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

Frequently asked questions

What is CVE-2025-39979?
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
Is CVE-2025-39979 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (6th percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2025-39979?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2025-39979 have an EU (EUVD) identifier?
Yes. CVE-2025-39979 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-34593.
When was CVE-2025-39979 published?
CVE-2025-39979 was published on 2025-10-15 and last updated on 2026-06-17.

References