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CVE-2026-80929 (GCVE-0-2026-80929)

Vulnerability from cvelistv5 – Published: 2026-09-11 19:42 – Updated: 2026-09-13 06:28
VLAI
Title
sysctl: move the "cad_pid" entry from pid_table[] to kern_reboot_table[]
Summary
In the Linux kernel, the following vulnerability has been resolved: sysctl: move the "cad_pid" entry from pid_table[] to kern_reboot_table[] cad_pid is global, and kill_cad_pid() is only used in the root namespace. However, due to pid_table_root_permissions(), a non-root user can unshare pid/user namespaces and modify it from the child namespace. This makes no sense and is simply wrong. Move it to kern_reboot_table[] where it logically belongs; this ensures that only GLOBAL_ROOT_UID can read/modify this sysctl. Note that this patch doesn't preserve "#ifdef CONFIG_PROC_SYSCTL" around the "cad_pid"; CONFIG_PROC_SYSCTL selects CONFIG_SYSCTL, so it is always set when kern_reboot_table[] is compiled.
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: e054bcbe7e7af2baad3752f1a4916a7fffc0457e , < e8527de7fea191fda704792a56081f9009aeec37 (git)
Affected: e054bcbe7e7af2baad3752f1a4916a7fffc0457e , < a09bc4eaa67e1a72df3b6d0beb3afeef1e1fdfcd (git)
Affected: e054bcbe7e7af2baad3752f1a4916a7fffc0457e , < 7170ca01623b399c97f2ae9d3e228badc1f25ea3 (git)
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Linux Linux Affected: 6.17
Unaffected: 0 , < 6.17 (semver)
Unaffected: 6.18.50 , ≤ 6.18.* (semver)
Unaffected: 7.2.4 , ≤ 7.2.* (semver)
Unaffected: 7.3-rc1 , ≤ * (original_commit_for_fix)
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "kernel/pid.c",
            "kernel/reboot.c"
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          "versions": [
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              "version": "7.2.4",
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              "operator": "OR"
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          "value": "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\u0027t 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."
        }
      ],
      "metrics": [
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            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
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              "lang": "en",
              "value": "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\u0027s 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\u0027s 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."
            }
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        "dateUpdated": "2026-09-13T06:28:10.105Z",
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        "shortName": "Linux"
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          "url": "https://git.kernel.org/stable/c/a09bc4eaa67e1a72df3b6d0beb3afeef1e1fdfcd"
        },
        {
          "url": "https://git.kernel.org/stable/c/7170ca01623b399c97f2ae9d3e228badc1f25ea3"
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    "cveId": "CVE-2026-80929",
    "datePublished": "2026-09-11T19:42:04.778Z",
    "dateReserved": "2026-08-26T14:34:25.802Z",
    "dateUpdated": "2026-09-13T06:28:10.105Z",
    "state": "PUBLISHED"
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            "value": "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\u0027t 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."
          }
        ],
        "id": "CVE-2026-80929",
        "lastModified": "2026-09-13T07:17:00.663",
        "metrics": {
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            {
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                "confidentialityImpact": "HIGH",
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      "current_release_date": "2026-09-14T13:54:03+00:00",
      "cve": "CVE-2026-80929",
      "id": "CVE-2026-80929",
      "initial_release_date": "2026-09-11T00:00:00+00:00",
      "product_status:known_affected": "14",
      "product_status:known_not_affected": "262",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: sysctl: move the \"cad_pid\" entry from pid_table[] to kern_reboot_table[]",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-80929.json",
      "version": "3"
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    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-09-15T01:06:17Z",
      "cve": "CVE-2026-80929",
      "id": "CVE-2026-80929",
      "initial_release_date": "2026-09-12T16:37:29Z",
      "product_status:known_not_affected": "353",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-80929",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-80929.json",
      "version": "4"
    }
  }
}



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  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
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  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


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