CVE-2026-64557 Bluetooth: L2CAP: Fix use-after-free in l2cap_sock_new_connection_cb()
A use-after-free in the Linux kernel Bluetooth L2CAP module allows attackers to execute arbitrary code or escalate privileges via crafted connections.
- 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-2026-64557?
CVE-2026-64557 is a high-severity use after free vulnerability in Linux, published on 29 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: L2CAP: Fix use-after-free in l2cap_sock_new_connection_cb()
l2cap_sock_new_connection_cb() returned l2cap_pi(sk)->chan after release_sock(parent). Once the parent lock is dropped the newly enqueued child socket sk is reachable via the accept queue, so another task can accept and free it before the callback dereferences sk, resulting in a use-after-free.
Rework the ->new_connection() op so the core, rather than the callback, owns the child channel's lifetime. The op now receives a pre-allocated new_chan and returns an errno instead of allocating and returning a channel. l2cap_new_connection() allocates the child channel and links it into the conn list via __l2cap_chan_add() before invoking the callback, so the conn-list reference keeps the channel alive once release_sock(parent) exposes the socket to other tasks.
Channel configuration that was duplicated in l2cap_sock_init() and the various new_connection callbacks is consolidated into l2cap_chan_set_defaults(), which now inherits from the parent channel when one is supplied.
Weakness: CWE-416
Which versions are affected by CVE-2026-64557?
How do I fix CVE-2026-64557?
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-2026-64557 being exploited?
There is no known exploitation of CVE-2026-64557 in the wild and no public exploit code.
Sources
Also known as AZL-94143, BELL-CVE-2026-64557, DEBIAN-CVE-2026-64557, GHSA-57gr-rx4p-h42m, ROOT-OS-DEBIAN-12-CVE-2026-64557, UBUNTU-CVE-2026-64557.