# CVE-2026-80827: USB: serial: option: fix slab OOB read in interrupt URB callback

> A malicious USB device can trigger a slab out-of-bounds read in the Linux kernel's option driver, potentially leaking memory or causing a crash.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 4 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-99644, BELL-CVE-2026-80827, DEBIAN-CVE-2026-80827, GHSA-459p-cph9-qpfg, UBUNTU-CVE-2026-80827

## What is CVE-2026-80827?

CVE-2026-80827 is a memory corruption vulnerability in Linux, published on 4 Sep 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.

### Official description

In the Linux kernel, the following vulnerability has been resolved:

USB: serial: option: fix slab OOB read in interrupt URB callback

The interrupt URB buffer is allocated in setup_port_interrupt_in() based
on the endpoint's wMaxPacketSize:

    buffer_size = usb_endpoint_maxp(epd);
    port->interrupt_in_buffer = kmalloc(buffer_size, GFP_KERNEL);

When a USB device declares wMaxPacketSize = 8 on its interrupt IN
endpoint, the buffer is allocated from kmalloc-8 cache (exactly
8 bytes).

If the device sends a short packet (actual_length < wMaxPacketSize),
the URB completes with status == 0 and the callback proceeds to read:

    data[sizeof(struct usb_ctrlrequest)]

which evaluates to data[8], accessing 1 byte beyond the allocated 8-byte
buffer. This results in a slab out-of-bounds read.

Fix this by adding the missing bounds check: first verify that the
actual length is large enough to contain the struct usb_ctrlrequest
header before accessing req_pkt->bRequestType and req_pkt->bRequest,
and then verify that there is an additional byte for the modem signal
state before reading data[sizeof(struct usb_ctrlrequest)] inside the
conditional.  Use sizeof(*req_pkt) instead of sizeof(struct
usb_ctrlrequest) for consistency.

[ johan: use dev_err(); split signals declaration and initialisation ]

## Which versions are affected by CVE-2026-80827?


## How do I fix CVE-2026-80827?

Apply the vendor's patch.

## Is CVE-2026-80827 being exploited?

There is no known exploitation of CVE-2026-80827 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-80827 and fix it if it is affected.

What it is: CVE-2026-80827 is a memory corruption vulnerability in Linux, published on 4 Sep 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-80827 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-2026-80827/ (Markdown: https://insights.sbomify.com/CVE-2026-80827/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-80827
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-80827
- OSV: https://osv.dev/vulnerability/CVE-2026-80827

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-80827/
Summaries are generated and may contain mistakes; the official description above is the record.