# CVE-2026-74711: hwmon: (pmbus) Fix type confusion in notification logic

> A type confusion vulnerability in the Linux kernel's PMBus driver allows out-of-bounds reads, potentially leading to information disclosure or system crashes.

- **Severity:** High 8.4 (`CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **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:** 22 Aug 2026
- **Updated:** 21 Oct 2026
- **Also known as:** AZL-97338, BELL-CVE-2026-74711, DEBIAN-CVE-2026-74711, GHSA-vxvv-ch48-4fvp, UBUNTU-CVE-2026-74711

## What is CVE-2026-74711?

CVE-2026-74711 is a high-severity memory corruption 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:

hwmon: (pmbus) Fix type confusion in notification logic

Sashiko reports:

At the start of the loop in pmbus_notify(), the code unconditionally casts
every attribute to a struct sensor_device_attribute:

drivers/hwmon/pmbus/pmbus_core.c:pmbus_notify() {
    for (i = 0; i < data->num_attributes; i++) {
        struct device_attribute *da = to_dev_attr(data->group.attrs[i]);
        struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
        int index = attr->index;
...
}

However, data->group.attrs can contain other types like struct
pmbus_samples_reg or struct pmbus_sensor, which only embed a base
struct device_attribute.

If da is a struct pmbus_samples_reg, dev_attr is the last member. Casting
it to struct sensor_device_attribute and reading the index field appears
to access memory past the end of the allocation, which might trigger a
slab-out-of-bounds read.

Additionally, if da is a struct pmbus_sensor, casting it causes the index
field to overlap with the page, phase, and reg fields. Could this produce
a garbage mask on little-endian systems that spuriously matches the target
reg, page, and flags during an alert?

Fix the problem by using struct sensor_device_attr in struct pmbus_sensor
and struct pmbus_label. Since those attributes never trigger a
notification, set the value of attr->index to -1 for them. Use this value
to distinguish from boolean attributes which _can_ trigger a notification
and use the index field to encode mask, page, and register values.

## Which versions are affected by CVE-2026-74711?


## How do I fix CVE-2026-74711?

Apply the vendor's patch.

## Is CVE-2026-74711 being exploited?

There is no known exploitation of CVE-2026-74711 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-74711 and fix it if it is affected.

What it is: CVE-2026-74711 is a high-severity memory corruption 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-2026-74711 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-2026-74711/ (Markdown: https://insights.sbomify.com/CVE-2026-74711/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-74711
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-74711
- OSV: https://osv.dev/vulnerability/CVE-2026-74711

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-74711/
Summaries are generated and may contain mistakes; the official description above is the record.