CVE-2025-39805
5.5 · MEDIUMOverview
CVE-2025-39805 is a medium-severity vulnerability affecting linux linux_kernel. It was published on September 16, 2025 and has a CVSS 3.1 base score of 5.5 (MEDIUM).
This vulnerability has a CVSS 3.1 base score of 5.5, rated MEDIUM. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.
Technical Description
In the Linux kernel, the following vulnerability has been resolved:
net: macb: fix unregister_netdev call order in macb_remove()
When removing a macb device, the driver calls phy_exit() before
unregister_netdev(). This leads to a WARN from kernfs:
------------[ cut here ]------------
kernfs: can not remove 'attached_dev', no directory
WARNING: CPU: 1 PID: 27146 at fs/kernfs/dir.c:1683
Call trace:
kernfs_remove_by_name_ns+0xd8/0xf0
sysfs_remove_link+0x24/0x58
phy_detach+0x5c/0x168
phy_disconnect+0x4c/0x70
phylink_disconnect_phy+0x6c/0xc0 [phylink]
macb_close+0x6c/0x170 [macb]
...
macb_remove+0x60/0x168 [macb]
platform_remove+0x5c/0x80
...
The warning happens because the PHY is being exited while the netdev
is still registered. The correct order is to unregister the netdev
before shutting down the PHY and cleaning up the MDIO bus.
Fix this by moving unregister_netdev() ahead of phy_exit() in
macb_remove().
Remediation
Check the references section for vendor advisories and patches from linux. Update linux_kernel to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
Affected Products
| Vendor | Product | Versions | Status |
|---|---|---|---|
| linux | linux_kernel | >= 5.18, < 6.12.45 | Affected |
References
Frequently Asked Questions
What is CVE-2025-39805?
CVE-2025-39805 is a medium-severity vulnerability affecting linux linux_kernel. It was published on September 16, 2025 and has a CVSS 3.1 base score of 5.5 (MEDIUM).
How severe is CVE-2025-39805?
This vulnerability has a CVSS 3.1 base score of 5.5, rated MEDIUM. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.
How do I fix or remediate CVE-2025-39805?
Check the references section for vendor advisories and patches from linux. Update linux_kernel to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How can CyberStrike help with CVE-2025-39805?
CyberStrike's AI-powered security agents can automatically detect CVE-2025-39805 across your infrastructure using autonomous pentesting, DAST scanning, and HackBrowser. The platform continuously monitors for known vulnerabilities and provides actionable remediation guidance prioritized by real-world exploitability.
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