{
  "affected": [
    {
      "ranges": [
        {
          "events": [
            {
              "introduced": "9ec52099e4b8678a60e9f93e41ad87885d64f3e6"
            },
            {
              "fixed": "ad72e2566643fff7f01666d845fb026898155e1f"
            },
            {
              "fixed": "9a17b0e053197a6a42cdc75e75a35b17aa662088"
            },
            {
              "fixed": "5a88f78df753993469dab4d1831f8fb4256a9468"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Linux",
        "name": "Kernel"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "2.6.19"
            },
            {
              "fixed": "6.18.53"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.19.0"
            },
            {
              "fixed": "7.2.7"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "database_specific": {
    "cna_assigner": "Linux",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/97xxx/CVE-2026-97938.json"
  },
  "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(\u0026old_pid-\u003ercu, ...) cannot be used here because free_pid()\nalso queues pid-\u003ercu; 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-\u003elevel\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)",
  "id": "CVE-2026-97938",
  "modified": "2026-09-27T03:30:38.409171377Z",
  "published": "2026-09-25T10:22:51.720Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/5a88f78df753993469dab4d1831f8fb4256a9468"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/9a17b0e053197a6a42cdc75e75a35b17aa662088"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/ad72e2566643fff7f01666d845fb026898155e1f"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/97xxx/CVE-2026-97938.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-97938"
    },
    {
      "type": "PACKAGE",
      "url": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
    }
  ],
  "schema_version": "1.9.0",
  "summary": "reboot: fix cad_pid use-after-free race"
}