CVE-2026-74536 Bluetooth: ISO: fix leaking sk after socket release
A memory leak in the Linux kernel Bluetooth ISO subsystem allows attackers to cause denial of service by exhausting kernel memory.
- 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-2026-74536?
CVE-2026-74536 is a memory corruption 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: fix leaking sk after socket release
iso_sock_kill() tests !sock_flag(sk, SOCK_ZAPPED) || sk->sk_socket || sock_flag(sk, SOCK_DEAD) for early return, but this is always true since sock_orphan(sk) sets SOCK_DEAD, so the sk reference released by socket always leaks, iso_sock_destruct is never called.
The socket reference also leaks when __iso_sock_close() does not set SOCK_ZAPPED, since iso_conn_del() does not call iso_sock_kill() after zapping.
Fix by replacing SOCK_DEAD by BT_SK_KILLED flag that is not used for something else, and lock_sock to ensure iso_sock_kill() puts sk only after socket release only once. Release and iso_conn_del may run concurrently. Call iso_sock_kill() from iso_conn_del() to clean sk up after zapping.
Remove call to iso_sock_kill() from iso_sock_close(), as it's generally no-op there.
Which versions are affected by CVE-2026-74536?
How do I fix CVE-2026-74536?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-74536 being exploited?
There is no known exploitation of CVE-2026-74536 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-74536, DEBIAN-CVE-2026-74536, GHSA-8vqw-g268-q22j, UBUNTU-CVE-2026-74536.