{"cve":"CVE-2026-63942","nvd":{"published":"2026-07-19T16:17:12.747","modified":"2026-10-19T21:17:13.253","status":"Undergoing Analysis","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nparport: Fix race between port and client registration\n\nThe parport subsystem registers port devices before they are fully\ninitialised, resulting in a race condition where client drivers such\nas lp can attach to ports that are not completely initialised or even\nbeing torn down.\n\nWhen the port and client drivers are built as modules and loaded\naround the same time during boot, this occasionally results in a\ncrash.  I was able to make this happen reliably in a VM with a\nPC-style parallel port by patching parport_pc to fail probing:\n\n> --- a/drivers/parport/parport_pc.c\n> +++ b/drivers/parport/parport_pc.c\n> @@ -2069,7 +2069,7 @@ static struct parport *__parport_pc_probe_port(unsigned long int base,\n>  \tif (!p)\n>  \t\tgoto out3;\n>\n> -\tbase_res = request_region(base, 3, p->name);\n> +\tbase_res = NULL;\n>  \tif (!base_res)\n>  \t\tgoto out4;\n>\n\nand then running:\n\n    while true; do\n        modprobe lp & modprobe parport_pc\n\twait\n\trmmod lp parport_pc\n    done\n\nfor a few seconds.\n\nIn the long term I think port registration should be changed to put\nthe call to device_add() inside parport_announce_port(), but since the\nlatter currently cannot fail this will require changing all port\ndrivers.\n\nFor now, add a flag to indicate whether a port has been \"announced\"\nand only try to attach client drivers to ports when the flag is set.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","score":7.8},"cwes":["CWE-362"],"references":["https://git.kernel.org/stable/c/15b1723c1472e802f9f7e69ae4e64f7dbf588848","https://git.kernel.org/stable/c/290f515c5e3b3900bc2fe24f179999fd08d23bfa","https://git.kernel.org/stable/c/51026cff1f4f3b762a0b5a07c727bd59cef45320","https://git.kernel.org/stable/c/74d6aae1df45d3414178986be743f946988fddf6","https://git.kernel.org/stable/c/a1e81b58da0179531bedf0b9f2811f5f992d5c4b"],"products":[],"source":"nvd","synced_at":"2026-10-21T03:43:09.190223697+00:00"},"epss":{"cve":"CVE-2026-63942","score":0.00131,"percentile":0.02662,"date":"2026-10-25"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}