CVE-2026-64126 Bluetooth: MGMT: validate Add Extended Advertising Data length
A local attacker with CAP_NET_ADMIN can read out-of-bounds memory via a malformed Bluetooth management command, potentially exposing sensitive kernel data.
- 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
What is CVE-2026-64126?
CVE-2026-64126 is a high-severity vulnerability in Linux kernel, published on 19 Jul 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: 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.
Weakness: CWE-125
Which versions are affected by CVE-2026-64126?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-64126?
Apply the vendor's patch.
Is CVE-2026-64126 being exploited?
There is no known exploitation of CVE-2026-64126 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-64126, DEBIAN-CVE-2026-64126, GHSA-ffq8-9j34-f4r6, ROOT-OS-UBUNTU-2204-CVE-2026-64126, UBUNTU-CVE-2026-64126.