# 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.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **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:** Yes
- **Published:** 16 Aug 2025
- **Updated:** 11 May 2026
- **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, ROOT-OS-UBUNTU-2204-CVE-2025-38535, ROOT-OS-UBUNTU-2404-CVE-2025-38535, UBUNTU-CVE-2025-38535

## 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: Debian Debian Linux, Linux kernel.

## How do I fix CVE-2025-38535?

Apply the vendor's patch.

## Is CVE-2025-38535 being exploited?

There is no known exploitation of CVE-2025-38535 in the wild and no public exploit code.

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## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-38535 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2025-38535 in the wild and no public exploit code.

Affected product: Debian Debian Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2025-38535/ (Markdown: https://insights.sbomify.com/CVE-2025-38535/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-38535
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-38535
- OSV: https://osv.dev/vulnerability/CVE-2025-38535

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-38535/
Summaries are generated and may contain mistakes; the official description above is the record.