# CVE-2026-98461: Bluetooth: hci_sock: validate event length before filtering

> A local attacker with Bluetooth access can trigger an out-of-bounds read in the Linux kernel by sending malformed HCI events, potentially causing a crash or leaking memory.

- **Severity:** Not scored
- **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:** 18 Oct 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-109364, BELL-CVE-2026-98461, DEBIAN-CVE-2026-98461, GHSA-xggg-9q4f-8rr9, UBUNTU-CVE-2026-98461

## What is CVE-2026-98461?

CVE-2026-98461 is a memory corruption vulnerability in Linux, published on 18 Oct 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: hci_sock: validate event length before filtering

is_filtered_packet() reads the event code from skb->data[0] without first
checking that the skb is nonempty. When an opcode filter is configured,
it also reads the command opcode at offsets 3 or 4 without checking that
a Command Complete or Command Status event is long enough.

hci_send_to_sock() invokes the filter before hci_event_packet() validates
the event header. A malformed event supplied by a controller or a vhci
device can therefore cause an out-of-bounds read.

Keep the unmasked event code for the opcode checks. The masked value is
needed for the 64-bit event bitmap, but using it to identify command events
aliases event codes above 0x3f. In particular, Synchronous Train Complete
(0x4f) was treated as Command Status (0x0f) even though its payload has no
opcode.

Reject actual command events that are too short for the field being
inspected. A truncated command event cannot match a configured opcode.

## Which versions are affected by CVE-2026-98461?


## How do I fix CVE-2026-98461?

Apply the vendor's patch.

## Is CVE-2026-98461 being exploited?

There is no known exploitation of CVE-2026-98461 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-98461 and fix it if it is affected.

What it is: CVE-2026-98461 is a memory corruption vulnerability in Linux, published on 18 Oct 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-2026-98461 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-2026-98461/ (Markdown: https://insights.sbomify.com/CVE-2026-98461/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-98461
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-98461
- OSV: https://osv.dev/vulnerability/CVE-2026-98461

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-98461/
Summaries are generated and may contain mistakes; the official description above is the record.