{
  "affected": [
    {
      "ranges": [
        {
          "events": [
            {
              "introduced": "76b6f5dfb3fda76fce1f9990d6fa58adc711122b"
            },
            {
              "fixed": "9e673bf5d88aa898e52cef5c87058c3fa845bc71"
            },
            {
              "fixed": "56ea4e86832d8abe8930394473566c194d189f85"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Linux",
        "name": "Kernel"
      },
      "ranges": [
        {
          "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-2026-97971.json"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnstree: check listing permission before taking a namespace reference\n\nlegitimize_ns() takes a reference on the candidate namespace before\nmay_list_ns() has decided whether the caller may see it. The\n__free(ns_put) cleanup on the denied path can drop the last reference to a\nmount namespace while we still hold the rcu read lock, and put_mnt_ns()\nmay sleep there. This is the same problem commit 2ec2aff3c8e2 (\"ns: make\nsure reference are dropped outside of rcu lock\") fixed for the put_user()\npath. Neither ns_requested() nor may_list_ns() needs a reference, both\nonly look at the namespace type and at the caller's own namespaces, so do\nthe checks first and take the reference last.\n\nSplat:\n\n  Voluntary context switch within RCU read-side critical section!\n  WARNING: kernel/rcu/tree_plugin.h:332 at rcu_note_context_switch+0x238/0x2a0, CPU#5: a/3442\n  CPU: 5 UID: 1000 PID: 3442 Comm: a Not tainted 7.0.0-30-generic #30-Ubuntu PREEMPT(lazy)\n  RIP: 0010:rcu_note_context_switch+0x238/0x2a0\n  Call Trace:\n   \u003cTASK\u003e\n   __schedule+0xcf/0x650\n   schedule+0x27/0x90\n   schedule_preempt_disabled+0x15/0x30\n   __mutex_lock.constprop.0+0x550/0xaf0\n   __mutex_lock_slowpath+0x13/0x20\n   mutex_lock+0x3b/0x50\n   exp_funnel_lock+0xb2/0x260\n   synchronize_rcu_expedited+0xe7/0x220\n   namespace_unlock+0x26a/0x320\n   put_mnt_ns+0xd3/0x120\n   mntns_put+0xe/0x20\n   do_listns+0x13e/0x560\n   __do_sys_listns+0x126/0x2d0\n   __x64_sys_listns+0x20/0x30\n   x64_sys_call+0x2366/0x2390\n   do_syscall_64+0x105/0x5a0\n   entry_SYSCALL_64_after_hwframe+0x76/0x7e\n   \u003c/TASK\u003e",
  "id": "CVE-2026-97971",
  "modified": "2026-09-27T03:30:19.449553910Z",
  "published": "2026-09-25T10:23:11.539Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/56ea4e86832d8abe8930394473566c194d189f85"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/9e673bf5d88aa898e52cef5c87058c3fa845bc71"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/97xxx/CVE-2026-97971.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-97971"
    },
    {
      "type": "PACKAGE",
      "url": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
    }
  ],
  "schema_version": "1.9.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "nstree: check listing permission before taking a namespace reference"
}