CVE Catalog

CVE-2026-63942

HighCVSS 7.8
Published: Updated: Translated: NVD NIST

Exploitation Probability (EPSS)

Low risk
0.16%

6th percentile - higher than 6% of all known CVEs

Summary

A race condition was found in the Linux kernel's parport subsystem between port and client registration. Ports are registered before full initialization, allowing clients like lp to attach to incomplete ports, causing system crashes.

Risk Assessment

The risk involves potential system crashes during concurrent loading of parport_pc and lp modules, especially in environments with parallel ports. This may disrupt services relying on these ports.

Recommendation

Update the Linux kernel to a version containing the fix (adding an 'announced' flag for ports). As a workaround, avoid loading parport_pc and lp modules simultaneously.

Other vulnerabilities in Linux kernel

See all
Original NVD description (English source)

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 rmmod lp parport_pc done for a few seconds. In the long term I think port registration should be changed to put the call to device_add() inside parport_announce_port(), but since the latter currently cannot fail this will require changing all port drivers. For now, add a flag to indicate whether a port has been "announced" and only try to attach client drivers to ports when the flag is set.

Vulnerability data from NVD (NIST) · CISA KEV · EPSS