# CVE-2026-90257: Bluetooth: virtio_bt: avoid OOB read of build info string

> A local attacker with Bluetooth access can trigger an out-of-bounds read in the Linux kernel, leaking adjacent memory contents to logs.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 17 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-102251, BELL-CVE-2026-90257, DEBIAN-CVE-2026-90257, GHSA-jc9v-mfxc-m9mm, UBUNTU-CVE-2026-90257

## What is CVE-2026-90257?

CVE-2026-90257 is a vulnerability in Linux, published on 17 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:

Bluetooth: virtio_bt: avoid OOB read of build info string

The virtbt_setup_zephyr() sends the Zephyr vendor command 0xfc08 (Read
Build Information) and hands the response to bt_dev_info() and
hci_set_fw_info() as a "%s" string starting at skb->data + 1, without
checking the length. A backend that answers with status only leaves that
pointer past the end of the received data, so the walk reads adjacent
slab memory until it meets a NUL. Those bytes reach the kernel log and
the firmware-info debugfs file.

To fix this, print the string with a bounded "%.*s" limited to
skb->len - 1. A short or unterminated response then prints as much as
arrived instead of failing setup.

This mirrors commit dd068ef04412 ("Bluetooth: bpa10x: avoid OOB read of
revision string in bpa10x_setup()"), which fixed the identical pattern.

## Which versions are affected by CVE-2026-90257?


## How do I fix CVE-2026-90257?

Apply the vendor's patch.

## Is CVE-2026-90257 being exploited?

There is no known exploitation of CVE-2026-90257 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-90257 and fix it if it is affected.

What it is: CVE-2026-90257 is a vulnerability in Linux, published on 17 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-2026-90257 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-2026-90257/ (Markdown: https://insights.sbomify.com/CVE-2026-90257/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-90257
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-90257
- OSV: https://osv.dev/vulnerability/CVE-2026-90257

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-90257/
Summaries are generated and may contain mistakes; the official description above is the record.