CVE-2025-39947 net/mlx5e: Harden uplink netdev access against device unbind
A missing null check in the Linux kernel mlx5e driver allows a local attacker to trigger a kernel panic via device unbind, causing denial of service.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-39947?
CVE-2025-39947 is a medium-severity vulnerability in Linux kernel, published on 4 Oct 2025. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
net/mlx5e: Harden uplink netdev access against device unbind
The function mlx5_uplink_netdev_get() gets the uplink netdevice pointer from mdev->mlx5e_res.uplink_netdev. However, the netdevice can be removed and its pointer cleared when unbound from the mlx5_core.eth driver. This results in a NULL pointer, causing a kernel panic.
BUG: unable to handle page fault for address: 0000000000001300 at RIP: 0010:mlx5e_vport_rep_load+0x22a/0x270 [mlx5_core] Call Trace: <TASK> mlx5_esw_offloads_rep_load+0x68/0xe0 [mlx5_core] esw_offloads_enable+0x593/0x910 [mlx5_core] mlx5_eswitch_enable_locked+0x341/0x420 [mlx5_core] mlx5_devlink_eswitch_mode_set+0x17e/0x3a0 [mlx5_core] devlink_nl_eswitch_set_doit+0x60/0xd0 genl_family_rcv_msg_doit+0xe0/0x130 genl_rcv_msg+0x183/0x290 netlink_rcv_skb+0x4b/0xf0 genl_rcv+0x24/0x40 netlink_unicast+0x255/0x380 netlink_sendmsg+0x1f3/0x420 __sock_sendmsg+0x38/0x60 __sys_sendto+0x119/0x180 do_syscall_64+0x53/0x1d0 entry_SYSCALL_64_after_hwframe+0x4b/0x53
Ensure the pointer is valid before use by checking it for NULL. If it is valid, immediately call netdev_hold() to take a reference, and preventing the netdevice from being freed while it is in use.
Weakness: CWE-476
Which versions are affected by CVE-2025-39947?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2025-39947?
Apply the vendor's patch.
Is CVE-2025-39947 being exploited?
There is no known exploitation of CVE-2025-39947 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as AZL-68181, AZL-75342, BELL-CVE-2025-39947, DEBIAN-CVE-2025-39947, GHSA-r3wm-5qjq-c8qp, ROOT-OS-DEBIAN-12-CVE-2025-39947 and 4 more.