{ "schema_version": "1.6.1", "id": "RPI-CVE-2026-80929", "modified": "2026-10-09T11:39:44Z", "upstream": [ "CVE-2026-80929" ], "published": "2026-09-11T19:47:07Z", "summary": "sysctl: move the \"cad_pid\" entry from pid_table[] to kern_reboot_table[]", "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nsysctl: move the \"cad_pid\" entry from pid_table[] to kern_reboot_table[]\n\ncad_pid is global, and kill_cad_pid() is only used in the root namespace.\n\nHowever, due to pid_table_root_permissions(), a non-root user can unshare\npid/user namespaces and modify it from the child namespace. This makes no\nsense and is simply wrong.\n\nMove it to kern_reboot_table[] where it logically belongs; this ensures\nthat only GLOBAL_ROOT_UID can read/modify this sysctl.\n\nNote that this patch doesn't preserve \"#ifdef CONFIG_PROC_SYSCTL\" around\nthe \"cad_pid\"; CONFIG_PROC_SYSCTL selects CONFIG_SYSCTL, so it is always\nset when kern_reboot_table[] is compiled.", "severity": [ { "type": "CVSS_V3", "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H" } ], "affected": [ { "package": { "ecosystem": "Raspberry Pi OS:13", "name": "linux" }, "versions": [ "1:6.18.29-1+rpt1", "1:6.18.33-1+rpt1", "1:6.18.34-1+rpt1", "1:6.18.39-1+rpt1" ], "ecosystem_specific": { "binaries": [ { "binary_name": "linux-image-6.18.29+rpt-rpi-2712", "binary_version": "1:6.18.29-1+rpt1" }, { "binary_name": "linux-image-6.18.29+rpt-rpi-v6", "binary_version": "1:6.18.29-1+rpt1" }, { "binary_name": "linux-image-6.18.29+rpt-rpi-v7", "binary_version": "1:6.18.29-1+rpt1" }, { "binary_name": "linux-image-6.18.29+rpt-rpi-v8", "binary_version": "1:6.18.29-1+rpt1" }, { "binary_name": "linux-image-6.18.29+rpt-rpi-v8-rt", "binary_version": "1:6.18.29-1+rpt1" }, { "binary_name": "linux-image-6.18.33+rpt-rpi-2712", "binary_version": "1:6.18.33-1+rpt1" }, { "binary_name": "linux-image-6.18.33+rpt-rpi-v6", "binary_version": "1:6.18.33-1+rpt1" }, { "binary_name": "linux-image-6.18.33+rpt-rpi-v7", "binary_version": "1:6.18.33-1+rpt1" }, { "binary_name": "linux-image-6.18.33+rpt-rpi-v8", "binary_version": "1:6.18.33-1+rpt1" }, { "binary_name": "linux-image-6.18.33+rpt-rpi-v8-rt", "binary_version": "1:6.18.33-1+rpt1" }, { "binary_name": "linux-image-6.18.34+rpt-rpi-2712", "binary_version": "1:6.18.34-1+rpt1" }, { "binary_name": "linux-image-6.18.34+rpt-rpi-v6", "binary_version": "1:6.18.34-1+rpt1" }, { "binary_name": "linux-image-6.18.34+rpt-rpi-v7", "binary_version": "1:6.18.34-1+rpt1" }, { "binary_name": "linux-image-6.18.34+rpt-rpi-v8", "binary_version": "1:6.18.34-1+rpt1" }, { "binary_name": "linux-image-6.18.34+rpt-rpi-v8-rt", "binary_version": "1:6.18.34-1+rpt1" }, { "binary_name": "linux-image-6.18.39+rpt-rpi-2712", "binary_version": "1:6.18.39-1+rpt1" }, { "binary_name": "linux-image-6.18.39+rpt-rpi-v6", "binary_version": "1:6.18.39-1+rpt1" }, { "binary_name": "linux-image-6.18.39+rpt-rpi-v7", "binary_version": "1:6.18.39-1+rpt1" }, { "binary_name": "linux-image-6.18.39+rpt-rpi-v8", "binary_version": "1:6.18.39-1+rpt1" }, { "binary_name": "linux-image-6.18.39+rpt-rpi-v8-rt", "binary_version": "1:6.18.39-1+rpt1" } ] }, "database_specific": { "per_version": { "1:6.18.29-1+rpt1": { "linux_commit": "66318c5b5cd8145a662303af12ed39ac07eb27cc", "upstream_version": "6.18.29", "assessment": "commit ancestry (strak rule)", "upstream_fixed": "6.18.50" }, "1:6.18.33-1+rpt1": { "linux_commit": "95b85bebbedcaedfa7ca79116ed38b7376fba412", "upstream_version": "6.18.33", "assessment": "commit ancestry (strak rule)", "upstream_fixed": "6.18.50" }, "1:6.18.34-1+rpt1": { "linux_commit": "c8c7494100e99ee05b11aaa4f0588a223a63d1af", "upstream_version": "6.18.34", "assessment": "commit ancestry (strak rule)", "upstream_fixed": "6.18.50" }, "1:6.18.39-1+rpt1": { "linux_commit": "60ea684a8ace97bb0db1a16e20753bdd6ab371ff", "upstream_version": "6.18.39", "assessment": "commit ancestry (strak rule)", "upstream_fixed": "6.18.50" } } } } ], "references": [ { "type": "ADVISORY", "url": "https://www.cve.org/CVERecord?id=CVE-2026-80929" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/e8527de7fea191fda704792a56081f9009aeec37" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/a09bc4eaa67e1a72df3b6d0beb3afeef1e1fdfcd" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/7170ca01623b399c97f2ae9d3e228badc1f25ea3" } ], "database_specific": { "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git", "upstream_modified": "2026-09-13T06:49:25Z", "severity": { "source": "kernel CNA", "cvss_v3_score": 7.8, "cvss_v3_severity": "High", "scenario": "AV:L - Unprivileged local processes reach proc_do_cad_pid() by opening and writing /proc/sys/kernel/cad_pid after creating user and PID namespaces; this is a procfs sysctl syscall path, not a network, adjacent-wireless, or physical-device handler.\nAC:L - The attacker fully controls namespace creation and concurrent sysctl reads/writes of the shared global cad_pid pointer, so the proc_do_cad_pid() use-after-free race does not depend on victim state, rare configs, or other conditions outside attacker influence.\nPR:L - pid_table_root_permissions() treats CAP_SYS_ADMIN or uid 0 in the PID namespace's user namespace as owner of the 0600 cad_pid sysctl, which an unprivileged user obtains by unsharing user and PID namespaces rather than needing init-namespace root.\nUI:N - The attacker triggers the flaw entirely through their own unshare, proc mount, and read/write of kernel.cad_pid; no other user must press Ctrl-Alt-Del, mount a filesystem, or take any action.\nS:U - Successful exploitation corrupts host kernel memory and hijacks the global cad_pid used by kill_cad_pid(); this remains inside the kernel's security authority and is not a VM, IOMMU, or DMA boundary bypass.\nC:H - Racing a cad_pid sysctl write (put_pid of the last reference) against a sysctl read use-after-frees struct pid in pid_vnr()/pid_nr_ns(), which per kernel CVSS guidance provides an arbitrary kernel-read primitive via slab reuse.\nI:H - The same use-after-free of struct pid is exploitable for heap spraying and control-flow hijack of kernel PID/signal paths, and the write also replaces host-global cad_pid so privileged kernel SIGINT/SIGPWR are redirected away from init.\nA:H - The use-after-free produces a kernel oops or panic on the pid_nr_ns() dereference of freed memory, as shown by the KASAN report; replacing cad_pid also persistently breaks host Ctrl-Alt-Del and power-button delivery to init." } } }