CVE-2026-63942

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

parport: Fix race between port and client registration

The parport subsystem registers port devices before they are fully

initialised, resulting in a race condition where client drivers such

as lp can attach to ports that are not completely initialised or even

being torn down.

When the port and client drivers are built as modules and loaded

around the same time during boot, this occasionally results in a

crash. I was able to make this happen reliably in a VM with a

PC-style parallel port by patching parport_pc to fail probing:

> --- a/drivers/parport/parport_pc.c

> +++ b/drivers/parport/parport_pc.c

> @@ -2069,7 +2069,7 @@ static struct parport *__parport_pc_probe_port(unsigned long int base,

> if (!p)

> goto out3;

>

> - base_res = request_region(base, 3, p->name);

> + base_res = NULL;

> if (!base_res)

> goto out4;

>

and then running:

while true; do

modprobe lp & modprobe parport_pc

wait

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References