# CVE-2026-80760: Bluetooth: MGMT: reject HCI_CMD_SYNC params_len above 255

> A local attacker can trigger a Bluetooth protocol desynchronization by sending malformed HCI commands, potentially causing denial of service or unexpected behavior.

- **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:** 4 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** BELL-CVE-2026-80760, DEBIAN-CVE-2026-80760, GHSA-p6r7-4gcj-hhqq, UBUNTU-CVE-2026-80760

## What is CVE-2026-80760?

CVE-2026-80760 is a vulnerability in Linux, published on 4 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: MGMT: reject HCI_CMD_SYNC params_len above 255

mgmt_hci_cmd_sync() checks that the message length agrees with params_len
but puts no upper bound on it. params_len is __le16 while the parameter
length in the HCI command header is a u8:

	struct hci_command_hdr {
		__le16	opcode;
		__u8	plen;
	} __packed;

hci_cmd_sync_alloc() assigns one to the other:

	hdr->plen = plen;

	if (plen)
		skb_put_data(skb, param, plen);

so a params_len of 256 leaves plen at 0 while all 256 bytes are still
appended. The frame handed to the driver then declares no parameters and
carries 256 of them. On a length framed transport such as H:4 the
controller takes the trailing bytes as the start of the next packet.

The mgmt socket MTU is HCI_MAX_FRAME_SIZE, so params_len can reach about
1KB this way. Commit 03f1700b9b4d ("Bluetooth: MGMT: reject malformed
HCI_CMD_SYNC commands") only made params_len agree with the message
length, a value that fits the message but not the header field is still
accepted.

Reject params_len that does not fit the header field.

## Which versions are affected by CVE-2026-80760?


## How do I fix CVE-2026-80760?

Apply the vendor's patch.

## Is CVE-2026-80760 being exploited?

There is no known exploitation of CVE-2026-80760 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-80760 and fix it if it is affected.

What it is: CVE-2026-80760 is a vulnerability in Linux, published on 4 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-2026-80760 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-2026-80760/ (Markdown: https://insights.sbomify.com/CVE-2026-80760/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-80760
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-80760
- OSV: https://osv.dev/vulnerability/CVE-2026-80760

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-80760/
Summaries are generated and may contain mistakes; the official description above is the record.