# CVE-2026-98771: usb: storage: sierra_ms: reject short SWoC info transfers

> A malicious USB device can leak stale kernel heap memory to unprivileged users via a sysfs attribute due to improper handling of short data transfers.

- **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:** 18 Oct 2026
- **Updated:** 21 Oct 2026
- **Also known as:** AZL-109214, BELL-CVE-2026-98771, DEBIAN-CVE-2026-98771, GHSA-7hw4-87pj-mc7h, UBUNTU-CVE-2026-98771

## What is CVE-2026-98771?

CVE-2026-98771 is a vulnerability in Linux, published on 18 Oct 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: storage: sierra_ms: reject short SWoC info transfers

sierra_get_swoc_info() requests sizeof(struct swoc_info) (60) bytes
from the device via usb_control_msg(), but its callers only treat a
negative return value as failure. A device that answers the
vendor-specific GetSwocInfo request with a short IN transfer is
therefore accepted, leaving the tail of the freshly allocated
(kmalloc(), non-zeroing) swoc_info buffer uninitialized.

truinst_show() subsequently prints swocInfo->rev, swocInfo->LinuxSKU
and swocInfo->LinuxVer from that buffer into the world-readable
(0444) "truinst" sysfs attribute. An emulated/malicious USB device
(VID 0x1199, PID 0x0fff) can exploit this to disclose up to 5 bytes
of stale kernel heap memory (kmalloc-64) to unprivileged userspace,
once per sysfs read, indefinitely. On kernels built without
init_on_alloc this leaks recently freed heap contents.

Only accept the transfer when the full structure was received.
sierra_ms_init() already retries failed queries, so well-behaved
devices are unaffected.

## Which versions are affected by CVE-2026-98771?


## How do I fix CVE-2026-98771?

Apply the vendor's patch.

## Is CVE-2026-98771 being exploited?

There is no known exploitation of CVE-2026-98771 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-98771 and fix it if it is affected.

What it is: CVE-2026-98771 is a vulnerability in Linux, published on 18 Oct 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-2026-98771 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-2026-98771/ (Markdown: https://insights.sbomify.com/CVE-2026-98771/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-98771
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-98771
- OSV: https://osv.dev/vulnerability/CVE-2026-98771

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-98771/
Summaries are generated and may contain mistakes; the official description above is the record.