CVE-2026-63942High· 7.8▾ TwilightIn 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 wh…
▾ Twilight zone — High severity, or a signal on a lesser flaw
impact 42.9 · likelihood 0 · exploitation 0
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Stakeholder-Specific Vulnerability Categorization from CISA's ADP record at CVE.org: whether exploitation is observed, whether an attack can be automated, and how much of the system is at stake. The CVSS score shown above comes from the assigning CNA record, not NVD.
Exploit-prediction probability, daily snapshots since Oct 16.
Disclosure to exploitation, from the record and what we observed since indexing it.
Disclosed via CVEORG
0.2%
Last analysed / modified upstream
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.
Linux >= 6fa45a22689722dac9f0e90c0931d4b34b334ede < f3378b0d7bd4605de89b083b2900788157a181ccLinux >= 6fa45a22689722dac9f0e90c0931d4b34b334ede < 290f515c5e3b3900bc2fe24f179999fd08d23bfaLinux >= 6fa45a22689722dac9f0e90c0931d4b34b334ede < d16548be2ea5058227d79799e81dab61c9bca8ecLinux >= 6fa45a22689722dac9f0e90c0931d4b34b334ede < 15b1723c1472e802f9f7e69ae4e64f7dbf588848Linux >= 6fa45a22689722dac9f0e90c0931d4b34b334ede < 51026cff1f4f3b762a0b5a07c727bd59cef45320Linux >= 6fa45a22689722dac9f0e90c0931d4b34b334ede < 74d6aae1df45d3414178986be743f946988fddf6Linux >= 6fa45a22689722dac9f0e90c0931d4b34b334ede < a1e81b58da0179531bedf0b9f2811f5f992d5c4bLinux >= 6fa45a22689722dac9f0e90c0931d4b34b334ede < ef15ccbb3e8640a723c42ad90eaf81d66ae02017Linux 4.2Refer to the linked advisories for vendor-supplied fixes and affected version ranges.
Connected by shared product, vendor, weakness, or advisory.
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