# CVE-2026-64427: HID: logitech-dj: Fix maxfield check in DJ short report validation

> A crafted HID descriptor causes a NULL pointer dereference in the Logitech DJ driver, leading to a kernel crash during device probe.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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:** 25 Jul 2026
- **Updated:** 19 Aug 2026
- **Also known as:** DEBIAN-CVE-2026-64427, GHSA-m6mf-crm7-82wq, ROOT-OS-UBUNTU-2204-CVE-2026-64427, UBUNTU-CVE-2026-64427

## What is CVE-2026-64427?

CVE-2026-64427 is a medium-severity vulnerability in Linux kernel, published on 25 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:

HID: logitech-dj: Fix maxfield check in DJ short report validation

Commit b6a57912854e ("HID: logitech-dj: Prevent REPORT_ID_DJ_SHORT
related user initiated OOB write") added validation for the DJ short
output report, but the error path dereferences rep->field[0] even when
rep->maxfield is zero.

Commit 8b9a097eb2fc ("HID: logitech-dj: fix wrong detection of bad
DJ_SHORT output report") made the check conditional on rep being present,
but a crafted descriptor can still create report ID 0x20 with only padding
output items. hid-core registers the report, ignores the padding field,
and leaves rep->maxfield as zero.

In that case the validation enters the rep->maxfield < 1 branch and then
dereferences rep->field[0]->report_count while printing the error message,
causing a NULL pointer dereference during probe. This is reproducible with
uhid by emulating a Logitech receiver with a padding-only DJ short output
report:

  BUG: KASAN: null-ptr-deref in logi_dj_probe+0xb1/0x754 [hid_logitech_dj]
  Read of size 4 at addr 0000000000000028 by task kworker/4:1/129
  ...
  Call Trace:
   logi_dj_probe+0xb1/0x754 [hid_logitech_dj]
   hid_device_probe+0x329/0x3f0 [hid]
   really_probe+0x162/0x570
   __device_attach+0x137/0x2c0
   bus_probe_device+0x38/0xc0
   device_add+0xa56/0xce0
   hid_add_device+0x19c/0x280 [hid]
   uhid_device_add_worker+0x2c/0xb0 [uhid]

Reject the zero-field report before printing the field report_count.

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2026-64427?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-64427?

Apply the vendor's patch.

## Is CVE-2026-64427 being exploited?

There is no known exploitation of CVE-2026-64427 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-2026-64427 and fix it if it is affected.

What it is: CVE-2026-64427 is a medium-severity vulnerability in Linux kernel, published on 25 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-2026-64427 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-2026-64427/ (Markdown: https://insights.sbomify.com/CVE-2026-64427/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-64427
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-64427
- OSV: https://osv.dev/vulnerability/CVE-2026-64427

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-64427/
Summaries are generated and may contain mistakes; the official description above is the record.