# CVE-2026-74733: gpio: pca953x: fix pca953x_irq_bus_sync_unlock regmap lock

> A race condition in the PCA953x GPIO driver allows concurrent threads to corrupt register states due to missing locks.

- **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:** 22 Aug 2026
- **Updated:** 21 Oct 2026
- **Also known as:** AZL-97329, BELL-CVE-2026-74733, DEBIAN-CVE-2026-74733, GHSA-p6rq-qpqh-5f25, UBUNTU-CVE-2026-74733

## What is CVE-2026-74733?

CVE-2026-74733 is a high-severity vulnerability in Linux, published on 22 Aug 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:

gpio: pca953x: fix pca953x_irq_bus_sync_unlock regmap lock

Locking is disabled in the regmap config as this driver uses its own
lock. This means that all calls to regmap functions (read or write) must
hold the i2c_lock. The function pca953x_irq_bus_sync_unlock() did not do
this, and it was therefore possible that multiple threads could cause an
incorrect register to be read/written.

A previous patch partly fixed this, but only protected the write to the
interrupt mask register, and not the read from the direction register.

## Which versions are affected by CVE-2026-74733?


## How do I fix CVE-2026-74733?

Apply the vendor's patch.

## Is CVE-2026-74733 being exploited?

There is no known exploitation of CVE-2026-74733 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-74733 and fix it if it is affected.

What it is: CVE-2026-74733 is a high-severity vulnerability in Linux, published on 22 Aug 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-2026-74733 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-2026-74733/ (Markdown: https://insights.sbomify.com/CVE-2026-74733/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-74733
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-74733
- OSV: https://osv.dev/vulnerability/CVE-2026-74733

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-74733/
Summaries are generated and may contain mistakes; the official description above is the record.