# CVE-2025-71143: clk: samsung: exynos-clkout: Assign .num before accessing .hws

> A missing initialization in the Samsung Exynos clock driver triggers a UBSAN bounds warning, potentially causing a kernel panic or denial of service.

- **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:** 14 Jan 2026
- **Updated:** 11 May 2026
- **Also known as:** BELL-CVE-2025-71143, DEBIAN-CVE-2025-71143, GHSA-7w9g-xvfr-q799, ROOT-OS-DEBIAN-13-CVE-2025-71143, ROOT-OS-UBUNTU-2404-CVE-2025-71143, UBUNTU-CVE-2025-71143

## What is CVE-2025-71143?

CVE-2025-71143 is a high-severity vulnerability in Linux kernel, published on 14 Jan 2026. 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:

clk: samsung: exynos-clkout: Assign .num before accessing .hws

Commit f316cdff8d67 ("clk: Annotate struct clk_hw_onecell_data with
__counted_by") annotated the hws member of 'struct clk_hw_onecell_data'
with __counted_by, which informs the bounds sanitizer (UBSAN_BOUNDS)
about the number of elements in .hws[], so that it can warn when .hws[]
is accessed out of bounds. As noted in that change, the __counted_by
member must be initialized with the number of elements before the first
array access happens, otherwise there will be a warning from each access
prior to the initialization because the number of elements is zero. This
occurs in exynos_clkout_probe() due to .num being assigned after .hws[]
has been accessed:

  UBSAN: array-index-out-of-bounds in drivers/clk/samsung/clk-exynos-clkout.c:178:18
  index 0 is out of range for type 'clk_hw *[*]'

Move the .num initialization to before the first access of .hws[],
clearing up the warning.

Weakness: CWE-129 (Improper Validation of Array Index)

## Which versions are affected by CVE-2025-71143?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2025-71143?

Apply the vendor's patch.

## Is CVE-2025-71143 being exploited?

There is no known exploitation of CVE-2025-71143 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-71143 and fix it if it is affected.

What it is: CVE-2025-71143 is a high-severity vulnerability in Linux kernel, published on 14 Jan 2026. 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-2025-71143 in the wild and no public exploit code.

Affected product: Linux kernel. 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-2025-71143/ (Markdown: https://insights.sbomify.com/CVE-2025-71143/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-71143
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-71143
- OSV: https://osv.dev/vulnerability/CVE-2025-71143

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-71143/
Summaries are generated and may contain mistakes; the official description above is the record.