CVE-2026-74537 Bluetooth: ISO: hold sk properly in iso_conn_ready
A race condition in the Linux kernel Bluetooth ISO subsystem allows a use-after-free, potentially enabling local attackers to execute code or escalate privileges.
- 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-2026-74537?
CVE-2026-74537 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: ISO: hold sk properly in iso_conn_ready
sk deref in iso_conn_ready must be done either under conn->lock, or holding a refcount, to avoid concurrent close. conn->sk is currently accessed without either:
[Task 1] [Task 2] iso_sock_release iso_conn_ready sk = conn->sk lock_sock(sk) conn->sk = NULL lock_sock(sk) release_sock(sk) iso_sock_kill(sk) UAF on sk deref
Fix possible UAF by holding sk refcount in iso_conn_ready(). Also recheck after lock_sock that the socket is still valid. Adjust locking so conn->sk is cleared only under lock_sock.
Which versions are affected by CVE-2026-74537?
How do I fix CVE-2026-74537?
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-2026-74537 being exploited?
There is no known exploitation of CVE-2026-74537 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-74537, DEBIAN-CVE-2026-74537, GHSA-4f56-g5vg-w2cg, UBUNTU-CVE-2026-74537.