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CVE-2025-40355
sysfs: check visibility before changing group attribute ownership
Published 2025-12-16 (10 months ago) by the Linux kernel CNA. Subsystem fs/sysfs. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2025-40355 in every release this site tracks, and what each one means in practice. Every status below is the one the Debian Security Team publishes for this CVE. source
| Release | Status | Version | What this means |
|---|---|---|---|
| Debian 12bookworm | vulnerable | 6.1.190-1 | No fix published anywhere yet, neither in Debian nor upstream for the series bookworm tracks. Watch the Debian tracker page for this CVE. Advisories for bookworm have historically landed a median of 23 days after publication. |
| Debian 13trixie | vulnerable | 6.12.113-1 | No fix published anywhere yet, neither in Debian nor upstream for the series trixie tracks. Watch the Debian tracker page for this CVE. Advisories for trixie have historically landed a median of 11 days after publication. |
| Debian 14forky | fixed | 6.17.6-1 | Update the kernel and reboot. Fixed in 6.17.6-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 6.17.6-1 | Update the kernel and reboot. Fixed in 6.17.6-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
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.
Where it lives
The fix touches these files. If the subsystem is one you do not use, the practical exposure is lower, though the package is still the vulnerable one.
fs/sysfs/group.c
- What this is
- DRIVER CORE, KOBJECTS, DEBUGFS AND SYSFSMAINTAINERS section matched on fs/sysfs/ · driver-core@lists.linux.dev · Supported
Check it on the machine
grep -w CONFIG_SYSFS /boot/config-$(uname -r)Reads the booted kernel's own configuration, on the machine and nowhere else. =y is built in, =m is a module, and an is not set line means the code is not there.
Show whether Debian builds this, per release
Debian builds this code. Every release below compiles the affected file into the kernels it ships.
- bookworm, trixie, forky, sidy
- y
- built into the kernel image on every flavour - only a patch removes it
- Build switch
- CONFIG_SYSFS
From the configuration Debian publishes for every kernel flavour it builds. It covers only the architectures Debian ships a linux-config package for, and nothing about a kernel you built yourself. Debian's own status above stays authoritative about the source package.MAINTAINERS kbuild Makefiles Debian linux-config packages
Signals
- Published
- 2025-12-16 (10 months ago)source
- CVSS
- no vector published, unrated
- Attack vector
- not published
- EPSS
- 0.19%, higher than 7.7% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- fs/sysfs
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 5.7 | 6.17.6 | ac2c526e1032 |
| 5.7 | 6.18 | c7fbb8218b4a |
Why the CNA scored it this way
The kernel CNA published no CVSS vector and no reasoning for CVE-2025-40355, which is why it is shown as unrated rather than given an invented score. 6,405 of the 20,413 CVEs here carry reasoning; this is not one of them.