{"schema":"threatline.record/2","record":{"id":"CVE-2026-97938","aliases":[],"summary":"reboot: fix cad_pid use-after-free race","details":"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 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)","categories":["Operating systems"],"product":"Linux","vendor":"Linux","ecosystem":null,"affected_ranges":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-97938","source_modified_at":"2026-10-21T12:53:45.385Z","fetched_at":"2026-10-23T18:45:31.882637Z","product":"Linux","vendor":"Linux","versions":[{"version":"9ec52099e4b8678a60e9f93e41ad87885d64f3e6","lessThan":"0c1a966bc047af2801a70b8eb13f9df5d7ab925f","status":"affected","versionType":"git"},{"version":"9ec52099e4b8678a60e9f93e41ad87885d64f3e6","lessThan":"ae3e53fe3c1241855e3a88f74877738349948c78","status":"affected","versionType":"git"},{"version":"9ec52099e4b8678a60e9f93e41ad87885d64f3e6","lessThan":"ad72e2566643fff7f01666d845fb026898155e1f","status":"affected","versionType":"git"},{"version":"9ec52099e4b8678a60e9f93e41ad87885d64f3e6","lessThan":"9a17b0e053197a6a42cdc75e75a35b17aa662088","status":"affected","versionType":"git"},{"version":"9ec52099e4b8678a60e9f93e41ad87885d64f3e6","lessThan":"5a88f78df753993469dab4d1831f8fb4256a9468","status":"affected","versionType":"git"}],"defaultStatus":"unaffected"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-97938","source_modified_at":"2026-10-21T12:53:45.385Z","fetched_at":"2026-10-23T18:45:31.882637Z","product":"Linux","vendor":"Linux","versions":[{"version":"2.6.19","status":"affected"},{"version":"0","lessThan":"2.6.19","status":"unaffected","versionType":"semver"},{"version":"6.6.160","lessThanOrEqual":"6.6.*","status":"unaffected","versionType":"semver"},{"version":"6.12.112","lessThanOrEqual":"6.12.*","status":"unaffected","versionType":"semver"},{"version":"6.18.53","lessThanOrEqual":"6.18.*","status":"unaffected","versionType":"semver"},{"version":"7.2.7","lessThanOrEqual":"7.2.*","status":"unaffected","versionType":"semver"},{"version":"7.3","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}],"defaultStatus":"affected"}],"fixed_versions":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-97938","source_modified_at":"2026-10-21T12:53:45.385Z","fetched_at":"2026-10-23T18:45:31.882637Z","package":{"name":"Linux","ecosystem":null},"version":"0c1a966bc047af2801a70b8eb13f9df5d7ab925f","basis":"first unaffected version stated in the CVE record"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-97938","source_modified_at":"2026-10-21T12:53:45.385Z","fetched_at":"2026-10-23T18:45:31.882637Z","package":{"name":"Linux","ecosystem":null},"version":"9a17b0e053197a6a42cdc75e75a35b17aa662088","basis":"first unaffected version stated in the CVE record"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-97938","source_modified_at":"2026-10-21T12:53:45.385Z","fetched_at":"2026-10-23T18:45:31.882637Z","package":{"name":"Linux","ecosystem":null},"version":"5a88f78df753993469dab4d1831f8fb4256a9468","basis":"first unaffected version stated in the CVE record"}],"cvss":null,"severity":null,"kev":{"listed":false},"epss":{"probability":0.002,"percentile":0.09326,"score_date":"2026-10-23"},"published_at":"2026-09-25T10:22:51.720Z","modified_at":"2026-10-21T12:53:45.385Z","provenance":[{"source":"CVE List","url":"https://www.cve.org/CVERecord?id=CVE-2026-97938","fetched_at":"2026-10-23T18:45:31.882637Z","source_modified_at":"2026-10-21T12:53:45.385Z"},{"source":"EPSS","url":"https://api.first.org/data/v1/epss?cve=CVE-2026-97938","fetched_at":"2026-10-23T18:42:43.628194Z","source_modified_at":"2026-10-23"}],"sources":["CVE List","EPSS"],"references":[{"source":"CVE List","url":"https://git.kernel.org/stable/c/0c1a966bc047af2801a70b8eb13f9df5d7ab925f"},{"source":"CVE List","url":"https://git.kernel.org/stable/c/ae3e53fe3c1241855e3a88f74877738349948c78"},{"source":"CVE List","url":"https://git.kernel.org/stable/c/ad72e2566643fff7f01666d845fb026898155e1f"},{"source":"CVE List","url":"https://git.kernel.org/stable/c/9a17b0e053197a6a42cdc75e75a35b17aa662088"},{"source":"CVE List","url":"https://git.kernel.org/stable/c/5a88f78df753993469dab4d1831f8fb4256a9468"}],"locations":[],"motoko_assessment":{"status":"requires_architecture_review","automatic_remediation":false},"cve_state":"PUBLISHED","classification":{"method":"product-first software-layer rules","rules_version":"2.1","matched_on":"product","confidence":"heuristic","reviewed":false},"change_timestamp":"2026-10-21T12:53:45.385Z","content_hash":"673ee3343065f92d77e6df2771476e05467fb3bf08dc8ece1eda716e4c8c5dfd"}}