CVE-2026-97971

Reference list NVD curates from the CNA record, vendor advisories, and third-party reports. The tag chips below are NVD's analyst-assigned categories.

• https://git.kernel.org/stable/c/56ea4e86832d8abe8930394473566c194d189f85 416baaa9-dc9f-4396-8d5f-8c081fb06d67
• https://git.kernel.org/stable/c/9e673bf5d88aa898e52cef5c87058c3fa845bc71 416baaa9-dc9f-4396-8d5f-8c081fb06d67

The full cvelistV5 record. Download as CVE-2026-97971.json.

{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "kernel/nstree.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "9e673bf5d88aa898e52cef5c87058c3fa845bc71",
              "status": "affected",
              "version": "76b6f5dfb3fda76fce1f9990d6fa58adc711122b",
              "versionType": "git"
            },
            {
              "lessThan": "56ea4e86832d8abe8930394473566c194d189f85",
              "status": "affected",
              "version": "76b6f5dfb3fda76fce1f9990d6fa58adc711122b",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "kernel/nstree.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.19"
            },
            {
              "lessThan": "6.19",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.7",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3-rc3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.7",
                  "versionStartIncluding": "6.19",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3-rc3",
                  "versionStartIncluding": "6.19",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "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   <TASK>\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   </TASK>"
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.8,
            "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": [
            {
              "lang": "en",
              "value": "AV:L - The bug is reached only through the local listns() syscall (SYSCALL_DEFINE4(listns) -> do_listns()/do_listns_userns() -> legitimize_ns()). No remote protocol supplies any input.\nAC:L - The attacker controls both sides of the race. One process loops listns() while another creates and tears down its own mount namespaces with unshare(CLONE_NEWUSER|CLONE_NEWNS), so legitimize_ns() ends up holding the last reference on the may_list_ns() denied path.\nPR:L - listns() has no capability gate, and may_list_ns() only filters what is returned after the reference is taken. The commit's splat shows the trigger from UID 1000, and the victim mount namespaces can be created without privilege through user namespaces.\nUI:N - The attacker's own syscalls produce both the listing and the namespace teardown. No other user takes part.\nS:U - This is corruption and a hang inside the kernel's own namespace and RCU handling. No hypervisor, IOMMU or other separately governed boundary is crossed.\nC:H - put_mnt_ns() queues call_rcu(mnt_ns_release_rcu) and then sleeps in synchronize_rcu_expedited() inside do_listns()'s rcu_read_lock. On non-preemptible-RCU kernels that lets the mnt_namespace be kfree'd, and next_ns_common(ns) then walks list pointers read from freed memory.\nI:H - After the use-after-free, the iterator hands a freed, reallocatable object to legitimize_ns(), which increments its refcount through ns_get_unless_inactive() and calls ns->ops->put(). That gives a write primitive and an indirect call through attacker-sprayable memory.\nA:H - On PREEMPT_RCU kernels, synchronize_rcu_expedited() called from within the caller's own RCU read-side section waits on itself and hangs the task. Elsewhere the result is a sleeping-in-atomic BUG or a use-after-free crash, and an unprivileged user can repeat it at will."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-25T14:41:46.399Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/9e673bf5d88aa898e52cef5c87058c3fa845bc71"
        },
        {
          "url": "https://git.kernel.org/stable/c/56ea4e86832d8abe8930394473566c194d189f85"
        }
      ],
      "title": "nstree: check listing permission before taking a namespace reference",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-97971",
    "datePublished": "2026-09-25T10:23:11.539Z",
    "dateReserved": "2026-09-25T10:18:58.207Z",
    "dateUpdated": "2026-09-25T14:41:46.399Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}