Linux Kernel up to 6.17.5 sysfs net/core/dev.c __dev_change_net_namespace privilege escalation

Summaryinfo

A vulnerability was found in Linux Kernel up to 6.17.5. It has been classified as critical. This impacts the function __dev_change_net_namespace of the file net/core/dev.c of the component sysfs. The manipulation leads to an unknown weakness. This vulnerability is traded as CVE-2025-40355. There is no exploit available. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability, which was classified as critical, has been found in Linux Kernel up to 6.17.5. This issue affects the function __dev_change_net_namespace of the file net/core/dev.c of the component sysfs. The impact remains unknown. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: sysfs: check visibility before changing group attribute ownership Since commit 0c17270f9b92 ("net: sysfs: Implement is_visible for phys_(port_id, port_name, switch_id)"), __dev_change_net_namespace() can hit WARN_ON() when trying to change owner of a file that isn't visible. See the trace below: WARNING: CPU: 6 PID: 2938 at net/core/dev.c:12410 __dev_change_net_namespace+0xb89/0xc30 CPU: 6 UID: 0 PID: 2938 Comm: incusd Not tainted 6.17.1-1-mainline #1 PREEMPT(full) 4b783b4a638669fb644857f484487d17cb45ed1f Hardware name: Framework Laptop 13 (AMD Ryzen 7040Series)/FRANMDCP07, BIOS 03.07 02/19/2025 RIP: 0010:__dev_change_net_namespace+0xb89/0xc30 [...] Call Trace: <TASK> ? if6_seq_show+0x30/0x50 do_setlink.isra.0+0xc7/0x1270 ? __nla_validate_parse+0x5c/0xcc0 ? security_capable+0x94/0x1a0 rtnl_newlink+0x858/0xc20 ? update_curr+0x8e/0x1c0 ? update_entity_lag+0x71/0x80 ? sched_balance_newidle+0x358/0x450 ? psi_task_switch+0x113/0x2a0 ? __pfx_rtnl_newlink+0x10/0x10 rtnetlink_rcv_msg+0x346/0x3e0 ? sched_clock+0x10/0x30 ? __pfx_rtnetlink_rcv_msg+0x10/0x10 netlink_rcv_skb+0x59/0x110 netlink_unicast+0x285/0x3c0 ? __alloc_skb+0xdb/0x1a0 netlink_sendmsg+0x20d/0x430 ____sys_sendmsg+0x39f/0x3d0 ? import_iovec+0x2f/0x40 ___sys_sendmsg+0x99/0xe0 __sys_sendmsg+0x8a/0xf0 do_syscall_64+0x81/0x970 ? __sys_bind+0xe3/0x110 ? syscall_exit_work+0x143/0x1b0 ? do_syscall_64+0x244/0x970 ? sock_alloc_file+0x63/0xc0 ? syscall_exit_work+0x143/0x1b0 ? do_syscall_64+0x244/0x970 ? alloc_fd+0x12e/0x190 ? put_unused_fd+0x2a/0x70 ? do_sys_openat2+0xa2/0xe0 ? syscall_exit_work+0x143/0x1b0 ? do_syscall_64+0x244/0x970 ? exc_page_fault+0x7e/0x1a0 entry_SYSCALL_64_after_hwframe+0x76/0x7e [...] </TASK> Fix this by checking is_visible() before trying to touch the attribute.

It is possible to read the advisory at git.kernel.org. The identification of this vulnerability is CVE-2025-40355 since 04/16/2025. The exploitation is known to be difficult. Technical details of the vulnerability are known, but there is no available exploit. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 02/21/2026).

The vulnerability scanner Nessus provides a plugin with the ID 298236 (SUSE SLES16 Security Update : kernel (SUSE-SU-2026:20220-1)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 6.17.6 eliminates this vulnerability. Applying the patch ac2c526e103285d80a0330b91a318f6c9276d35a/c7fbb8218b4ad35fec0bd2256d2b9c8d60331f33 is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (298236) and CERT Bund (WID-SEC-2025-2868). Be aware that VulDB is the high quality source for vulnerability data.

Affected

• Debian Linux
• Amazon Linux 2
• Red Hat Enterprise Linux
• Ubuntu Linux
• SUSE Linux
• Oracle Linux
• SUSE openSUSE
• RESF Rocky Linux
• Open Source Linux Kernel

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 6.17.0
• 6.17.1
• 6.17.2
• 6.17.3
• 6.17.4
• 6.17.5

License

• open-source

Website

• Vendor: https://www.kernel.org/

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Entryinfo

Be aware that VulDB is the high quality source for vulnerability data.

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