CVE-2026-63942
parport: Fix race between port and client registration
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.
INFO
Published Date :
July 19, 2026, 4:17 p.m.
Last Modified :
July 27, 2026, 5:44 p.m.
Remotely Exploit :
No
Source :
416baaa9-dc9f-4396-8d5f-8c081fb06d67
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | HIGH | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
Solution
- Update the Linux kernel to the latest stable version.
- Ensure parport and client drivers are loaded sequentially.
- Review and apply the announced port flag fix.
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Common Attack Pattern Enumeration and Classification (CAPEC)
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weaknesses.
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-
CVE Modified by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Jul. 20, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H -
New CVE Received by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Jul. 19, 2026
Action Type Old Value New Value Added Affected [{'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '6fa45a22689722dac9f0e90c0931d4b34b334ede', 'lessThan': 'f3378b0d7bd4605de89b083b2900788157a181cc', 'versionType': 'git'}, {'status': 'affected', 'version': '6fa45a22689722dac9f0e90c0931d4b34b334ede', 'lessThan': '290f515c5e3b3900bc2fe24f179999fd08d23bfa', 'versionType': 'git'}, {'status': 'affected', 'version': '6fa45a22689722dac9f0e90c0931d4b34b334ede', 'lessThan': 'd16548be2ea5058227d79799e81dab61c9bca8ec', 'versionType': 'git'}, {'status': 'affected', 'version': '6fa45a22689722dac9f0e90c0931d4b34b334ede', 'lessThan': '15b1723c1472e802f9f7e69ae4e64f7dbf588848', 'versionType': 'git'}, {'status': 'affected', 'version': '6fa45a22689722dac9f0e90c0931d4b34b334ede', 'lessThan': '51026cff1f4f3b762a0b5a07c727bd59cef45320', 'versionType': 'git'}, {'status': 'affected', 'version': '6fa45a22689722dac9f0e90c0931d4b34b334ede', 'lessThan': '74d6aae1df45d3414178986be743f946988fddf6', 'versionType': 'git'}, {'status': 'affected', 'version': '6fa45a22689722dac9f0e90c0931d4b34b334ede', 'lessThan': 'a1e81b58da0179531bedf0b9f2811f5f992d5c4b', 'versionType': 'git'}, {'status': 'affected', 'version': '6fa45a22689722dac9f0e90c0931d4b34b334ede', 'lessThan': 'ef15ccbb3e8640a723c42ad90eaf81d66ae02017', 'versionType': 'git'}], 'programFiles': ['drivers/parport/share.c', 'include/linux/parport.h'], 'defaultStatus': 'unaffected'}, {'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '4.2'}, {'status': 'unaffected', 'version': '0', 'lessThan': '4.2', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '5.10.259', 'versionType': 'semver', 'lessThanOrEqual': '5.10.*'}, {'status': 'unaffected', 'version': '5.15.210', 'versionType': 'semver', 'lessThanOrEqual': '5.15.*'}, {'status': 'unaffected', 'version': '6.1.176', 'versionType': 'semver', 'lessThanOrEqual': '6.1.*'}, {'status': 'unaffected', 'version': '6.6.143', 'versionType': 'semver', 'lessThanOrEqual': '6.6.*'}, {'status': 'unaffected', 'version': '6.12.93', 'versionType': 'semver', 'lessThanOrEqual': '6.12.*'}, {'status': 'unaffected', 'version': '6.18.35', 'versionType': 'semver', 'lessThanOrEqual': '6.18.*'}, {'status': 'unaffected', 'version': '7.0.12', 'versionType': 'semver', 'lessThanOrEqual': '7.0.*'}, {'status': 'unaffected', 'version': '7.1', 'versionType': 'original_commit_for_fix', 'lessThanOrEqual': '*'}], 'programFiles': ['drivers/parport/share.c', 'include/linux/parport.h'], 'defaultStatus': 'affected'}] Added 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. Added Reference https://git.kernel.org/stable/c/15b1723c1472e802f9f7e69ae4e64f7dbf588848 Added Reference https://git.kernel.org/stable/c/290f515c5e3b3900bc2fe24f179999fd08d23bfa Added Reference https://git.kernel.org/stable/c/51026cff1f4f3b762a0b5a07c727bd59cef45320 Added Reference https://git.kernel.org/stable/c/74d6aae1df45d3414178986be743f946988fddf6 Added Reference https://git.kernel.org/stable/c/a1e81b58da0179531bedf0b9f2811f5f992d5c4b Added Reference https://git.kernel.org/stable/c/d16548be2ea5058227d79799e81dab61c9bca8ec Added Reference https://git.kernel.org/stable/c/ef15ccbb3e8640a723c42ad90eaf81d66ae02017 Added Reference https://git.kernel.org/stable/c/f3378b0d7bd4605de89b083b2900788157a181cc