# CVE-2026-89622: HID: mcp2221: clear rxbuf after I2C/SMBus transfer completes

> A use-after-free in the Linux kernel MCP2221 HID driver allows attackers to execute arbitrary code or escalate privileges via crafted I2C reports.

- **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:** 11 Sep 2026
- **Updated:** 21 Oct 2026
- **Also known as:** AZL-100335, BELL-CVE-2026-89622, DEBIAN-CVE-2026-89622, GHSA-hmph-x79p-jwjq, UBUNTU-CVE-2026-89622

## What is CVE-2026-89622?

CVE-2026-89622 is a high-severity use after free 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: mcp2221: clear rxbuf after I2C/SMBus transfer completes

mcp_i2c_smbus_read() stores the caller-supplied buffer pointer in
mcp->rxbuf for the duration of a transfer but never clears it when the
transfer finishes or times out. Once the caller frees or reuses the
buffer, mcp->rxbuf becomes a dangling pointer. A delayed or spurious
MCP2221_I2C_GET_DATA report can then drive mcp2221_raw_event() to
memcpy device data into the freed memory, causing a write
use-after-free.

Route all return paths through a single exit point that clears
mcp->rxbuf and mcp->rxbuf_size, so that the existing !mcp->rxbuf guard
in the raw_event handler can reject any report arriving after the
transfer has ended.

## Which versions are affected by CVE-2026-89622?


## How do I fix CVE-2026-89622?

Apply the vendor's patch.

## Is CVE-2026-89622 being exploited?

There is no known exploitation of CVE-2026-89622 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-89622 and fix it if it is affected.

What it is: CVE-2026-89622 is a high-severity use after free 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-2026-89622 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-2026-89622/ (Markdown: https://insights.sbomify.com/CVE-2026-89622/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-89622
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-89622
- OSV: https://osv.dev/vulnerability/CVE-2026-89622

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-89622/
Summaries are generated and may contain mistakes; the official description above is the record.