CVE-2025-40284 Bluetooth: MGMT: cancel mesh send timer when hdev removed
A use-after-free vulnerability in the Linux kernel Bluetooth MGMT subsystem allows a local attacker to cause a system crash by triggering a timer after device removal.
- 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-2025-40284?
CVE-2025-40284 is a high-severity use after free vulnerability in Linux, published on 6 Dec 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: MGMT: cancel mesh send timer when hdev removed
mesh_send_done timer is not canceled when hdev is removed, which causes crash if the timer triggers after hdev is gone.
Cancel the timer when MGMT removes the hdev, like other MGMT timers.
Should fix the BUG: sporadically seen by BlueZ test bot (in "Mesh - Send cancel - 1" test).
Log: ------ BUG: KASAN: slab-use-after-free in run_timer_softirq+0x76b/0x7d0 ... Freed by task 36: kasan_save_stack+0x24/0x50 kasan_save_track+0x14/0x30 __kasan_save_free_info+0x3a/0x60 __kasan_slab_free+0x43/0x70 kfree+0x103/0x500 device_release+0x9a/0x210 kobject_put+0x100/0x1e0 vhci_release+0x18b/0x240 ------
Which versions are affected by CVE-2025-40284?
How do I fix CVE-2025-40284?
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-2025-40284 being exploited?
There is no known exploitation of CVE-2025-40284 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2025-40284, DEBIAN-CVE-2025-40284, GHSA-5w6m-vxmj-7w4c, ROOT-OS-DEBIAN-12-CVE-2025-40284, ROOT-OS-DEBIAN-13-CVE-2025-40284, ROOT-OS-UBUNTU-2204-CVE-2025-40284 and 2 more.