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VulnerabilityPublished Updated

CVE-2026-63942: Linux kernel · parport: Fix race between port and client registration

Affects Linux kernelSource CVE Database V5

0

Not known to be exploited · CVSS 7.8 High · fixed in f3378b0d7bd4605de89b083b2900788157a181cc : patch Linux kernel soon.

Data as of 26 Oct 2026, 17:30 UTC

CVSS 3.1 base score
7.8High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.1% chance of exploitation in 30 days – higher than 2% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CISA SSVC
Exploitation
No evidence of active exploitation and no public proof of concept
Automatable
Attackers cannot reliably automate steps 1–4 of the kill chain
Technical impact
Total control over the software or total information disclosure

CISA SSVC assessment, 2026-10-16.

Patch
Available – fixed in f3378b0d7bd4605de89b083b2900788157a181cc, ef15ccbb3e8640a723c42ad90eaf81d66ae02017, d16548be2ea5058227d79799e81dab61c9bca8ec +5
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 19 Jul 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

ProductAffectedFixed in
LinuxLinuxAffected
  • ≥ 6fa45a22689722dac9f0e90c0931d4b34b334ede, < f3378b0d7bd4605de89b083b2900788157a181cc
Fixed in
  • f3378b0d7bd4605de89b083b2900788157a181cc
LinuxLinuxAffected
  • ≥ 6fa45a22689722dac9f0e90c0931d4b34b334ede, < ef15ccbb3e8640a723c42ad90eaf81d66ae02017
Fixed in
  • ef15ccbb3e8640a723c42ad90eaf81d66ae02017
LinuxLinuxAffected
  • ≥ 6fa45a22689722dac9f0e90c0931d4b34b334ede, < d16548be2ea5058227d79799e81dab61c9bca8ec
Fixed in
  • d16548be2ea5058227d79799e81dab61c9bca8ec
LinuxLinuxAffected
  • ≥ 6fa45a22689722dac9f0e90c0931d4b34b334ede, < a1e81b58da0179531bedf0b9f2811f5f992d5c4b
Fixed in
  • a1e81b58da0179531bedf0b9f2811f5f992d5c4b
LinuxLinuxAffected
  • ≥ 6fa45a22689722dac9f0e90c0931d4b34b334ede, < 51026cff1f4f3b762a0b5a07c727bd59cef45320
Fixed in
  • 51026cff1f4f3b762a0b5a07c727bd59cef45320
LinuxLinuxAffected
  • ≥ 6fa45a22689722dac9f0e90c0931d4b34b334ede, < 290f515c5e3b3900bc2fe24f179999fd08d23bfa
Fixed in
  • 290f515c5e3b3900bc2fe24f179999fd08d23bfa

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 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.

References

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