# CVE-2026-63932: iio: chemical: mhz19b: reject oversized serial replies

> A buffer overflow in the Linux kernel MHZ19B sensor driver allows attackers to cause denial of service or execute code via oversized serial replies.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 19 Jul 2026
- **Updated:** 19 Jul 2026
- **Also known as:** BELL-CVE-2026-63932, DEBIAN-CVE-2026-63932, GHSA-vrpq-2gcp-g727, UBUNTU-CVE-2026-63932

## What is CVE-2026-63932?

CVE-2026-63932 is a memory corruption vulnerability in Linux, published on 19 Jul 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:

iio: chemical: mhz19b: reject oversized serial replies

mhz19b_receive_buf() appends each serdev chunk into the fixed
MHZ19B_CMD_SIZE receive buffer and advances buf_idx by len without
checking that the chunk fits in the remaining space. A large callback
can therefore overflow st->buf before the command path validates the
reply.

Reset the reply state before each command and reject oversized serial
replies before copying them into the fixed buffer. When an oversized
reply is detected, wake the waiter and report -EMSGSIZE instead of
overwriting st->buf.

## Which versions are affected by CVE-2026-63932?


## How do I fix CVE-2026-63932?

Apply the vendor's patch.

## Is CVE-2026-63932 being exploited?

There is no known exploitation of CVE-2026-63932 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-63932 and fix it if it is affected.

What it is: CVE-2026-63932 is a memory corruption vulnerability in Linux, published on 19 Jul 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-2026-63932 in the wild and no public exploit code.

Affected product: 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-2026-63932/ (Markdown: https://insights.sbomify.com/CVE-2026-63932/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-63932
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-63932
- OSV: https://osv.dev/vulnerability/CVE-2026-63932

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-63932/
Summaries are generated and may contain mistakes; the official description above is the record.