CVE-2025-40120

CVE-2025-40120 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: usb: asix: hold PM usage ref to avoid PM/MDIO + RTNL deadlock Prevent USB runtime PM (autosuspend) for AX88772* in bind. usbnet enables runtime PM (autosuspend) by default, so disabling it via the usb_driver flag is ineffective. On AX88772B, autosuspend shows no measurable power saving with current driver (no link partner, admin up/down). The ~0.453 W -> ~0.248 W drop on v6.1 comes from phylib powering the PHY off on admin-down, not from USB autosuspend. The real hazard is that with runtime PM enabled, ndo_open() (under RTNL) may synchronously trigger autoresume (usb_autopm_get_interface()) into asix_resume() while the USB PM lock is held. Resume paths then invoke phylink/phylib and MDIO, which also expect RTNL, leading to possible deadlocks or PM lock vs MDIO wake issues. To avoid this, keep the device runtime-PM active by taking a usage reference in ax88772_bind() and dropping it in unbind(). A non-zero PM usage count blocks runtime suspend regardless of userspace policy (.../power/control - pm_runtime_allow/forbid), making this approach robust against sysfs overrides. Holding a runtime-PM usage ref does not affect system-wide suspend; system sleep/resume callbacks continue to run as before.

Frequently asked questions

What is CVE-2025-40120?
In the Linux kernel, the following vulnerability has been resolved: net: usb: asix: hold PM usage ref to avoid PM/MDIO + RTNL deadlock Prevent USB runtime PM (autosuspend) for AX88772* in bind. usbnet enables runtime PM (autosuspend) by default, so disabling it via the usb_driver flag is ineffective. On AX88772B, autosuspend shows no measurable power saving with current driver (no link partner, admin up/down). The ~0.453 W -> ~0.248 W drop on v6.1 comes from phylib powering the PHY off on admin-down, not from USB autosuspend. The real hazard is that with runtime PM enabled, ndo_open() (under RTNL) may synchronously trigger autoresume (usb_autopm_get_interface()) into asix_resume() while the USB PM lock is held. Resume paths then invoke phylink/phylib and MDIO, which also expect RTNL, leading to possible deadlocks or PM lock vs MDIO wake issues. To avoid this, keep the device runtime-PM active by taking a usage reference in ax88772_bind() and dropping it in unbind(). A non-zero PM usage count blocks runtime suspend regardless of userspace policy (.../power/control - pm_runtime_allow/forbid), making this approach robust against sysfs overrides. Holding a runtime-PM usage ref does not affect system-wide suspend; system sleep/resume callbacks continue to run as before.
Is CVE-2025-40120 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (8th percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2025-40120?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2025-40120 have an EU (EUVD) identifier?
Yes. CVE-2025-40120 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-124963.
When was CVE-2025-40120 published?
CVE-2025-40120 was published on 2025-11-12 and last updated on 2026-06-17.

References