CVE-2025-38592 Bluetooth: hci_devcd_dump: fix out-of-bounds via dev_coredumpv
A use-after-free vulnerability in the Linux kernel Bluetooth driver allows attackers to cause a system crash via out-of-bounds memory access.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-38592?
CVE-2025-38592 is a high-severity use after free vulnerability in Linux kernel, published on 19 Aug 2025. 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: hci_devcd_dump: fix out-of-bounds via dev_coredumpv
Currently both dev_coredumpv and skb_put_data in hci_devcd_dump use hdev->dump.head. However, dev_coredumpv can free the buffer. From dev_coredumpm_timeout documentation, which is used by dev_coredumpv:
> Creates a new device coredump for the given device. If a previous one hasn't > been read yet, the new coredump is discarded. The data lifetime is determined > by the device coredump framework and when it is no longer needed the @free > function will be called to free the data.
If the data has not been read by the userspace yet, dev_coredumpv will discard new buffer, freeing hdev->dump.head. This leads to vmalloc-out-of-bounds error when skb_put_data tries to access hdev->dump.head.
A crash report from syzbot illustrates this:
================================================================== BUG: KASAN: vmalloc-out-of-bounds in skb_put_data include/linux/skbuff.h:2752 [inline] BUG: KASAN: vmalloc-out-of-bounds in hci_devcd_dump+0x142/0x240 net/bluetooth/coredump.c:258 Read of size 140 at addr ffffc90004ed5000 by task kworker/u9:2/5844
CPU: 1 UID: 0 PID: 5844 Comm: kworker/u9:2 Not tainted 6.14.0-syzkaller-10892-g4e82c87058f4 #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025 Workqueue: hci0 hci_devcd_timeout Call Trace: <TASK> __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:408 [inline] print_report+0xc3/0x670 mm/kasan/report.c:521 kasan_report+0xe0/0x110 mm/kasan/report.c:634 check_region_inline mm/kasan/generic.c:183 [inline] kasan_check_range+0xef/0x1a0 mm/kasan/generic.c:189 __asan_memcpy+0x23/0x60 mm/kasan/shadow.c:105 skb_put_data include/linux/skbuff.h:2752 [inline] hci_devcd_dump+0x142/0x240 net/bluetooth/coredump.c:258 hci_devcd_timeout+0xb5/0x2e0 net/bluetooth/coredump.c:413 process_one_work+0x9cc/0x1b70 kernel/workqueue.c:3238 process_scheduled_works kernel/workqueue.c:3319 [inline] worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400 kthread+0x3c2/0x780 kernel/kthread.c:464 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:153 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 </TASK>
The buggy address ffffc90004ed5000 belongs to a vmalloc virtual mapping Memory state around the buggy address: ffffc90004ed4f00: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 ffffc90004ed4f80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 >ffffc90004ed5000: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 ^ ffffc90004ed5080: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 ffffc90004ed5100: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 ==================================================================
To avoid this issue, reorder dev_coredumpv to be called after skb_put_data that does not free the data.
Weakness: CWE-125
Which versions are affected by CVE-2025-38592?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2025-38592?
Apply the vendor's patch.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2025-38592 being exploited?
There is no known exploitation of CVE-2025-38592 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2025-38592, GHSA-3qph-5xxf-77fc, UBUNTU-CVE-2025-38592.