# CVE-2026-89628: HID: picolcd: clamp eeprom debugfs read to bytes actually received

> A local attacker with root privileges can read adjacent kernel memory via a crafted HID device response in the picolcd driver.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 11 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-100241, BELL-CVE-2026-89628, DEBIAN-CVE-2026-89628, GHSA-84x9-cxq8-hpgq, UBUNTU-CVE-2026-89628

## What is CVE-2026-89628?

CVE-2026-89628 is a vulnerability in Linux, published on 11 Sep 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: picolcd: clamp eeprom debugfs read to bytes actually received

picolcd_debug_eeprom_read() trusts resp->raw_data[2] -- a length byte
supplied by the device in its REPORT_EE_DATA reply -- clamped only to
the caller's read() count:

	ret = resp->raw_data[2];
	if (ret > s)
		ret = s;
	if (copy_to_user(u, resp->raw_data+3, ret))

It never checks resp->raw_size, the number of bytes picolcd_raw_event()
actually copied into the 64-byte raw_data[] of the kmalloc'd struct
picolcd_pending. A device (or a spoofed picoLCD) returning a length byte
of 0xff, read with a count >= 255, makes copy_to_user() read past
raw_data[] into adjacent slab memory and return it to userspace through
the debugfs "eeprom" file:

	BUG: KASAN: slab-out-of-bounds in _copy_to_user
	Read of size 255 ... picolcd_debug_eeprom_read+0x214/0x2f0 [hid_picolcd]

The debug-dump path in the same file already validates the device length
byte against the received size before trusting it; this read does not.
The file is created S_IRUSR (root-only) and a crafted device is needed,
so it is neither unprivileged- nor remotely-triggerable.

Clamp the copy length to resp->raw_size - 3 (the payload actually
received, minus the 3-byte header), floored at 0 for short replies.

## Which versions are affected by CVE-2026-89628?


## How do I fix CVE-2026-89628?

Apply the vendor's patch.

## Is CVE-2026-89628 being exploited?

There is no known exploitation of CVE-2026-89628 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-89628 and fix it if it is affected.

What it is: CVE-2026-89628 is a vulnerability in Linux, published on 11 Sep 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-2026-89628 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-2026-89628/ (Markdown: https://insights.sbomify.com/CVE-2026-89628/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-89628
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-89628
- OSV: https://osv.dev/vulnerability/CVE-2026-89628

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-89628/
Summaries are generated and may contain mistakes; the official description above is the record.