CVE-2026-64004 net/iucv: fix locking in .getsockopt
A race condition in the Linux kernel's IUCV socket implementation allows local users to crash the system via a NULL pointer dereference.
- 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-2026-64004?
CVE-2026-64004 is a high-severity vulnerability in Linux kernel, published on 19 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:
net/iucv: fix locking in .getsockopt
Mirror iucv_sock_setsockopt() and wrap the whole switch in lock_sock()/release_sock(). The pre-existing SO_MSGLIMIT-only lock becomes redundant and is removed.
Any AF_IUCV HIPER user can potentially crash the kernel by racing recvmsg() with getsockopt(SO_MSGSIZE): the SO_MSGSIZE arm dereferences iucv->hs_dev->mtu after iucv_sock_close() (called from the racing recvmsg()) has set hs_dev to NULL, producing a NULL pointer dereference oops.
Which versions are affected by CVE-2026-64004?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-64004?
Apply the vendor's patch.
Is CVE-2026-64004 being exploited?
There is no known exploitation of CVE-2026-64004 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-64004, DEBIAN-CVE-2026-64004, GHSA-f6mc-xr5x-m669, ROOT-OS-UBUNTU-2204-CVE-2026-64004, UBUNTU-CVE-2026-64004.