{"id":"CVE-2026-97938","title":"In the Linux kernel, the following vulnerability has been resolved:\n\nreboot: fix cad_pid use-after-free race\n\ncad_pid is a single kernel-wide struct pid pointer","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nreboot: fix cad_pid use-after-free race\n\ncad_pid is a single kernel-wide struct pid pointer. proc_do_cad_pid()\nreads it and passes it to pid_vnr() without protecting th…","severity":"high","cvss":7,"cvssVector":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H","cwe":["CWE-825","CWE-416"],"vendor":"Linux","product":"Linux","affected":["Linux >= 9ec52099e4b8678a60e9f93e41ad87885d64f3e6 < ae3e53fe3c1241855e3a88f74877738349948c78","Linux >= 9ec52099e4b8678a60e9f93e41ad87885d64f3e6 < ad72e2566643fff7f01666d845fb026898155e1f","Linux >= 9ec52099e4b8678a60e9f93e41ad87885d64f3e6 < 9a17b0e053197a6a42cdc75e75a35b17aa662088","Linux >= 9ec52099e4b8678a60e9f93e41ad87885d64f3e6 < 5a88f78df753993469dab4d1831f8fb4256a9468","Linux 2.6.19"],"published":"2026-09-25","updated":"2026-10-03","sourceUpdated":"2026-10-03T11:18:19.390","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-97938","references":[{"url":"https://git.kernel.org/stable/c/5a88f78df753993469dab4d1831f8fb4256a9468","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/9a17b0e053197a6a42cdc75e75a35b17aa662088","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/ad72e2566643fff7f01666d845fb026898155e1f","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/ae3e53fe3c1241855e3a88f74877738349948c78","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-97938.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-97938"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2541188"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-97938"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-97938"},{"url":"https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-97938.mbox"},{"url":"https://git.kernel.org/stable/c/0c1a966bc047af2801a70b8eb13f9df5d7ab925f"},{"url":"https://kernelcve.org/list/?q=CVE-2026-97938"}],"tags":["nvd","cve.org","csaf","vex","red-hat"],"epss":0.00206,"epssPercentile":0.10585,"cvssSource":"vendor","ingestedAt":"2026-09-25T11:06:38.883Z","slug":"CVE-2026-97938","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nreboot: fix cad_pid use-after-free race\n\ncad_pid is a single kernel-wide struct pid pointer. proc_do_cad_pid()\nreads it and passes it to pid_vnr() without protecting the lifetime of\nthe referenced struct pid. A concurrent writer can replace cad_pid and\ndrop the final reference to the old struct pid after the reader has\nloaded the pointer but before pid_vnr() has finished dereferencing it,\ncausing a use-after-free.\n\nkill_cad_pid() has the same lifetime race when it passes cad_pid to\nkill_pid().\n\nAt the time this issue was reported, an unprivileged user could reach the\nsysctl through user and PID namespaces because cad_pid was registered in\npid_table[]. Moving cad_pid back to the global reboot sysctl table\ncorrected that namespace and permission mismatch, but did not fix the\nunderlying lifetime race.\n\nFix this by treating cad_pid as an RCU-protected pointer at both read\nsites and by waiting for a grace period before dropping the old reference\non the write side.\n\ncall_rcu(&old_pid->rcu, ...) cannot be used here because free_pid()\nalso queues pid->rcu; queueing the same rcu_head twice can corrupt the\nRCU callback list.\n\nOriginal KASAN crash stack:\n  kernel/pid.c:545 pid_nr_ns()        # reads freed pid->level\n  kernel/pid.c:556 pid_vnr()          # calls pid_nr_ns()\n  kernel/pid.c:775 proc_do_cad_pid()  # calls pid_vnr(cad_pid)\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.\n\n## Vendor advisories\n\n- **Red Hat VEX** · Moderate · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · no fix planned: Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8, … · updated 2026-10-23 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-97938.json)","depth":"twilight","depthScore":39,"depthScoreParts":{"impact":38.5,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[{"seq":213421,"id":"CVE-2026-97938","ts":1790754715124,"field":"cvss","old":null,"new":"7"},{"seq":213420,"id":"CVE-2026-97938","ts":1790754715124,"field":"severity","old":"none","new":"high"}]}