{"id":"CVE-2026-97938","revision":"a519602478204c54b0c2a0cf958cfc1b","records":[{"revision":"a519602478204c54b0c2a0cf958cfc1b","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-97938","aliases":[],"title":"reboot: fix cad_pid use-after-free race","description":"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)","state":0,"publishedAt":"2026-09-25T10:22:51.72+00:00","modifiedAt":"2026-10-21T12:53:45.385+00:00","affected":[{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"product\": \"Linux\",\n                    \"vendor\": \"Linux\",\n                    \"defaultStatus\": \"unaffected\",\n                    \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n                    \"programFiles\": [\n                        \"include/linux/sched.h\",\n                        \"include/linux/sched/signal.h\",\n                        \"init/main.c\",\n                        \"kernel/reboot.c\",\n                        \"kernel/signal.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"9ec52099e4b8678a60e9f93e41ad87885d64f3e6\",\n                            \"lessThan\": \"0c1a966bc047af2801a70b8eb13f9df5d7ab925f\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"9ec52099e4b8678a60e9f93e41ad87885d64f3e6\",\n                            \"lessThan\": \"ae3e53fe3c1241855e3a88f74877738349948c78\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"9ec52099e4b8678a60e9f93e41ad87885d64f3e6\",\n                            \"lessThan\": \"ad72e2566643fff7f01666d845fb026898155e1f\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"9ec52099e4b8678a60e9f93e41ad87885d64f3e6\",\n                            \"lessThan\": \"9a17b0e053197a6a42cdc75e75a35b17aa662088\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"9ec52099e4b8678a60e9f93e41ad87885d64f3e6\",\n                            \"lessThan\": \"5a88f78df753993469dab4d1831f8fb4256a9468\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        }\n                    ]\n                }"},{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"product\": \"Linux\",\n                    \"vendor\": \"Linux\",\n                    \"defaultStatus\": \"affected\",\n                    \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n                    \"programFiles\": [\n                        \"include/linux/sched.h\",\n                        \"include/linux/sched/signal.h\",\n                        \"init/main.c\",\n                        \"kernel/reboot.c\",\n                        \"kernel/signal.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"2.6.19\",\n                            \"status\": \"affected\"\n                        },\n                        {\n                            \"version\": \"0\",\n                            \"lessThan\": \"2.6.19\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.6.160\",\n                            \"lessThanOrEqual\": \"6.6.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.12.112\",\n                            \"lessThanOrEqual\": \"6.12.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.18.53\",\n                            \"lessThanOrEqual\": \"6.18.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.2.7\",\n                            \"lessThanOrEqual\": \"7.2.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.3\",\n                            \"lessThanOrEqual\": \"*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"original_commit_for_fix\"\n                        }\n                    ]\n                }"}],"metrics":[],"references":["https://git.kernel.org/stable/c/0c1a966bc047af2801a70b8eb13f9df5d7ab925f","https://git.kernel.org/stable/c/ae3e53fe3c1241855e3a88f74877738349948c78","https://git.kernel.org/stable/c/ad72e2566643fff7f01666d845fb026898155e1f","https://git.kernel.org/stable/c/9a17b0e053197a6a42cdc75e75a35b17aa662088","https://git.kernel.org/stable/c/5a88f78df753993469dab4d1831f8fb4256a9468"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-97938","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-97938","identifiers":["CVE-2026-97938"]},"retained":false,"historicalAffected":[]}],"coverage":[]}