# CVE-2026-43380: hwmon: (pmbus/q54sj108a2) fix stack overflow in debugfs read

> A stack buffer overflow in the Linux kernel q54sj108a2 PMBus driver allows attackers to cause denial of service or execute arbitrary code via debugfs.

- **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:** 8 May 2026
- **Updated:** 5 Aug 2026
- **Also known as:** BELL-CVE-2026-43380, DEBIAN-CVE-2026-43380, GHSA-7c6h-fgvg-xw96, ROOT-OS-UBUNTU-2204-CVE-2026-43380, ROOT-OS-UBUNTU-2404-CVE-2026-43380, UBUNTU-CVE-2026-43380

## What is CVE-2026-43380?

CVE-2026-43380 is a high-severity memory corruption vulnerability in Linux kernel, published on 8 May 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:

hwmon: (pmbus/q54sj108a2) fix stack overflow in debugfs read

The q54sj108a2_debugfs_read function suffers from a stack buffer overflow
due to incorrect arguments passed to bin2hex(). The function currently
passes 'data' as the destination and 'data_char' as the source.

Because bin2hex() converts each input byte into two hex characters, a
32-byte block read results in 64 bytes of output. Since 'data' is only
34 bytes (I2C_SMBUS_BLOCK_MAX + 2), this writes 30 bytes past the end
of the buffer onto the stack.

Additionally, the arguments were swapped: it was reading from the
zero-initialized 'data_char' and writing to 'data', resulting in
all-zero output regardless of the actual I2C read.

Fix this by:
1. Expanding 'data_char' to 66 bytes to safely hold the hex output.
2. Correcting the bin2hex() argument order and using the actual read count.
3. Using a pointer to select the correct output buffer for the final
   simple_read_from_buffer call.

Weakness: CWE-125 (Out-of-bounds Read)

## Which versions are affected by CVE-2026-43380?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-43380?

Apply the vendor's patch.

## Is CVE-2026-43380 being exploited?

There is no known exploitation of CVE-2026-43380 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-2026-43380 and fix it if it is affected.

What it is: CVE-2026-43380 is a high-severity memory corruption vulnerability in Linux kernel, published on 8 May 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-2026-43380 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-2026-43380/ (Markdown: https://insights.sbomify.com/CVE-2026-43380/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-43380
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-43380
- OSV: https://osv.dev/vulnerability/CVE-2026-43380

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-43380/
Summaries are generated and may contain mistakes; the official description above is the record.