# CVE-2024-56653: Bluetooth: btmtk: avoid UAF in btmtk_process_coredump

> A use-after-free vulnerability in the Linux kernel's Bluetooth driver allows attackers to cause a denial of service or potentially execute code via crafted Bluetooth packets.

- **Severity:** High 8.8 (`CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 27 Dec 2024
- **Updated:** 5 Aug 2026
- **Also known as:** AZL-54875, BELL-CVE-2024-56653, DEBIAN-CVE-2024-56653, GHSA-jgxj-ff5p-q3r5, UBUNTU-CVE-2024-56653, USN-7492-1, USN-7492-2

## What is CVE-2024-56653?

CVE-2024-56653 is a high-severity use after free vulnerability in Linux kernel, published on 27 Dec 2024. 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: btmtk: avoid UAF in btmtk_process_coredump

hci_devcd_append may lead to the release of the skb, so it cannot be
accessed once it is called.

==================================================================
BUG: KASAN: slab-use-after-free in btmtk_process_coredump+0x2a7/0x2d0 [btmtk]
Read of size 4 at addr ffff888033cfabb0 by task kworker/0:3/82

CPU: 0 PID: 82 Comm: kworker/0:3 Tainted: G     U             6.6.40-lockdep-03464-g1d8b4eb3060e #1 b0b3c1cc0c842735643fb411799d97921d1f688c
Hardware name: Google Yaviks_Ufs/Yaviks_Ufs, BIOS Google_Yaviks_Ufs.15217.552.0 05/07/2024
Workqueue: events btusb_rx_work [btusb]
Call Trace:
 <TASK>
 dump_stack_lvl+0xfd/0x150
 print_report+0x131/0x780
 kasan_report+0x177/0x1c0
 btmtk_process_coredump+0x2a7/0x2d0 [btmtk 03edd567dd71a65958807c95a65db31d433e1d01]
 btusb_recv_acl_mtk+0x11c/0x1a0 [btusb 675430d1e87c4f24d0c1f80efe600757a0f32bec]
 btusb_rx_work+0x9e/0xe0 [btusb 675430d1e87c4f24d0c1f80efe600757a0f32bec]
 worker_thread+0xe44/0x2cc0
 kthread+0x2ff/0x3a0
 ret_from_fork+0x51/0x80
 ret_from_fork_asm+0x1b/0x30
 </TASK>

Allocated by task 82:
 stack_trace_save+0xdc/0x190
 kasan_set_track+0x4e/0x80
 __kasan_slab_alloc+0x4e/0x60
 kmem_cache_alloc+0x19f/0x360
 skb_clone+0x132/0xf70
 btusb_recv_acl_mtk+0x104/0x1a0 [btusb]
 btusb_rx_work+0x9e/0xe0 [btusb]
 worker_thread+0xe44/0x2cc0
 kthread+0x2ff/0x3a0
 ret_from_fork+0x51/0x80
 ret_from_fork_asm+0x1b/0x30

Freed by task 1733:
 stack_trace_save+0xdc/0x190
 kasan_set_track+0x4e/0x80
 kasan_save_free_info+0x28/0xb0
 ____kasan_slab_free+0xfd/0x170
 kmem_cache_free+0x183/0x3f0
 hci_devcd_rx+0x91a/0x2060 [bluetooth]
 worker_thread+0xe44/0x2cc0
 kthread+0x2ff/0x3a0
 ret_from_fork+0x51/0x80
 ret_from_fork_asm+0x1b/0x30

The buggy address belongs to the object at ffff888033cfab40
 which belongs to the cache skbuff_head_cache of size 232
The buggy address is located 112 bytes inside of
 freed 232-byte region [ffff888033cfab40, ffff888033cfac28)

The buggy address belongs to the physical page:
page:00000000a174ba93 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x33cfa
head:00000000a174ba93 order:1 entire_mapcount:0 nr_pages_mapped:0 pincount:0
anon flags: 0x4000000000000840(slab|head|zone=1)
page_type: 0xffffffff()
raw: 4000000000000840 ffff888100848a00 0000000000000000 0000000000000001
raw: 0000000000000000 0000000080190019 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888033cfaa80: fb fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc
 ffff888033cfab00: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb
>ffff888033cfab80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                     ^
 ffff888033cfac00: fb fb fb fb fb fc fc fc fc fc fc fc fc fc fc fc
 ffff888033cfac80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Check if we need to call hci_devcd_complete before calling
hci_devcd_append. That requires that we check data->cd_info.cnt >=
MTK_COREDUMP_NUM instead of data->cd_info.cnt > MTK_COREDUMP_NUM, as we
increment data->cd_info.cnt only once the call to hci_devcd_append
succeeds.

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2024-56653?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2024-56653?

Apply the vendor's patch.

## Is CVE-2024-56653 being exploited?

There is no known exploitation of CVE-2024-56653 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2024-56653 and fix it if it is affected.

What it is: CVE-2024-56653 is a high-severity use after free vulnerability in Linux kernel, published on 27 Dec 2024. 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-2024-56653 in the wild and no public exploit code.

Affected product: Linux kernel. 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-2024-56653/ (Markdown: https://insights.sbomify.com/CVE-2024-56653/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-56653
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-56653
- OSV: https://osv.dev/vulnerability/CVE-2024-56653

---
From sbomify Insights: https://insights.sbomify.com/CVE-2024-56653/
Summaries are generated and may contain mistakes; the official description above is the record.