CVE-2025-38535 phy: tegra: xusb: Fix unbalanced regulator disable in UTMI PHY mode
A logic error in the Linux kernel Tegra USB PHY driver causes unbalanced regulator disables, potentially triggering kernel warnings and system instability.
- 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-2025-38535?
CVE-2025-38535 is a high-severity denial of service vulnerability in Debian Debian Linux, published on 16 Aug 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:
phy: tegra: xusb: Fix unbalanced regulator disable in UTMI PHY mode
When transitioning from USB_ROLE_DEVICE to USB_ROLE_NONE, the code assumed that the regulator should be disabled. However, if the regulator is marked as always-on, regulator_is_enabled() continues to return true, leading to an incorrect attempt to disable a regulator which is not enabled.
This can result in warnings such as:
[ 250.155624] WARNING: CPU: 1 PID: 7326 at drivers/regulator/core.c:3004 _regulator_disable+0xe4/0x1a0 [ 250.155652] unbalanced disables for VIN_SYS_5V0
To fix this, we move the regulator control logic into tegra186_xusb_padctl_id_override() function since it's directly related to the ID override state. The regulator is now only disabled when the role transitions from USB_ROLE_HOST to USB_ROLE_NONE, by checking the VBUS_ID register. This ensures that regulator enable/disable operations are properly balanced and only occur when actually transitioning to/from host mode.
Which versions are affected by CVE-2025-38535?
It affects 2 products.
Products include Debian Debian Linux, Linux kernel.
How do I fix CVE-2025-38535?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2025-38535 being exploited?
There is no known exploitation of CVE-2025-38535 in the wild and no public exploit code.
Other vulnerabilities in Debian Debian Linux
Sources
Also known as BELL-CVE-2025-38535, DEBIAN-CVE-2025-38535, GHSA-gvwq-wr3v-v8jg, ROOT-OS-DEBIAN-11-CVE-2025-38535, ROOT-OS-DEBIAN-12-CVE-2025-38535, ROOT-OS-DEBIAN-13-CVE-2025-38535 and 3 more.