CVE-2026-74540 Bluetooth: L2CAP: fix UAF in l2cap_le_connect_rsp
A use-after-free in the Linux kernel Bluetooth L2CAP handler allows attackers to potentially execute code or escalate privileges via concurrent channel operations.
- 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-2026-74540?
CVE-2026-74540 is a high-severity use after free vulnerability in Linux, published on 15 Aug 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: L2CAP: fix UAF in l2cap_le_connect_rsp
l2cap_le_connect_rsp() obtains a channel via __l2cap_get_chan_by_ident() but neither holds a reference nor uses l2cap_chan_hold_unless_zero() before locking and operating on it. A concurrent l2cap_chan_del() triggered by a remote disconnect can free the channel between the lookup and l2cap_chan_lock(), causing a use-after-free.
The BR/EDR counterpart l2cap_connect_rsp() and the sibling handler l2cap_le_command_rej() already use l2cap_chan_hold_unless_zero() to safely hold a reference, but l2cap_le_connect_rsp() was left unprotected.
Fix by adding l2cap_chan_hold_unless_zero() after the ident lookup and l2cap_chan_put() on the exit path, consistent with other L2CAP response handlers.
Which versions are affected by CVE-2026-74540?
How do I fix CVE-2026-74540?
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-2026-74540 being exploited?
There is no known exploitation of CVE-2026-74540 in the wild and no public exploit code.
Sources
Also known as AZL-96479, BELL-CVE-2026-74540, DEBIAN-CVE-2026-74540, GHSA-j62w-h52r-54ch, UBUNTU-CVE-2026-74540.