CVE-2026-53116 s390/ap: use generic driver_override infrastructure

High 7.8 Published 24 Jun 2026 Updated 24 Jun 2026

A race condition in the Linux kernel s390 AP bus driver allows a use-after-free, potentially enabling local attackers to execute code or escalate privileges.

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-2026-53116?

CVE-2026-53116 is a high-severity use after free vulnerability in Linux kernel, published on 24 Jun 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:

s390/ap: use generic driver_override infrastructure

When the AP masks are updated via apmask_store() or aqmask_store(), ap_bus_revise_bindings() is called after ap_attr_mutex has been released.

This calls __ap_revise_reserved(), which accesses the driver_override field without holding any lock, racing against a concurrent driver_override_store() that may free the old string, resulting in a potential UAF.

Fix this by using the driver-core driver_override infrastructure, which protects all accesses with an internal spinlock.

Note that unlike most other buses, the AP bus does not check driver_override in its match() callback; the override is checked in ap_device_probe() and __ap_revise_reserved() instead.

Also note that we do not enable the driver_override feature of struct bus_type, as AP - in contrast to most other buses - passes "" to sysfs_emit() when the driver_override pointer is NULL. Thus, printing "\n" instead of "(null)\n".

Additionally, AP has a custom counter that is modified in the corresponding custom driver_override_store().

Weakness: CWE-416

Which versions are affected by CVE-2026-53116?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2026-53116?

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-2026-53116 being exploited?

There is no known exploitation of CVE-2026-53116 in the wild and no public exploit code.

All Linux kernel vulnerabilities

Sources

Also known as DEBIAN-CVE-2026-53116, GHSA-r2jg-mcxg-628g, UBUNTU-CVE-2026-53116.