{
  "affected": [
    {
      "ranges": [
        {
          "events": [
            {
              "introduced": "1ac3629bf012592cb0320e52a1cceb319a05ad17"
            },
            {
              "fixed": "104a51265042b4424085741c963cb858ac29ec0b"
            },
            {
              "fixed": "0146467a2fce845cb6629979c3e9c58dd3d3a6a3"
            },
            {
              "fixed": "2f3e6638aebc0ab8afb8b4e9816ea9a1cad85378"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Linux",
        "name": "Kernel"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "6.9.0"
            },
            {
              "fixed": "6.18.51"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.19.0"
            },
            {
              "fixed": "7.2.5"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "database_specific": {
    "cna_assigner": "Linux",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/90xxx/CVE-2026-90039.json"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nNFSD: Guard admin state-revocation walks with NFSD_NET_UP\n\nWriting to /proc/fs/nfsd/unlock_filesystem, or sending the\nNFSD_CMD_UNLOCK_FILESYSTEM or NFSD_CMD_UNLOCK_EXPORT netlink command,\nwalks the NFSv4 client hash tables to revoke open state and cancel\nasync COPY operations.  All three handlers gate that walk on\nnn-\u003enfsd_serv, but a listener added via portlist or netlink\nlistener_set sets nn-\u003enfsd_serv before any nfsd thread starts.\nnfsd_startup_net() has not yet allocated nn-\u003econf_id_hashtbl, so the\nwalkers dereference a NULL table.  A local administrator with\nCAP_SYS_ADMIN can crash the kernel this way without ever starting the\nserver.\n\nnn-\u003enfsd_serv is set when the service is created, which precedes\ntable allocation.  NFSD_NET_UP instead brackets the window where the\ntables are live: set at the end of nfsd_startup_net() and cleared in\nnfsd_shutdown_net() after they are freed, both under nfsd_mutex.\nGating the three unlock paths on NFSD_NET_UP fixes the startup-time\nNULL dereference while preserving the earlier post-shutdown\nuse-after-free fix.",
  "id": "CVE-2026-90039",
  "modified": "2026-09-18T03:31:00.345322483Z",
  "published": "2026-09-16T10:33:38.091Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/0146467a2fce845cb6629979c3e9c58dd3d3a6a3"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/104a51265042b4424085741c963cb858ac29ec0b"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/2f3e6638aebc0ab8afb8b4e9816ea9a1cad85378"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/90xxx/CVE-2026-90039.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-90039"
    },
    {
      "type": "PACKAGE",
      "url": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
    }
  ],
  "schema_version": "1.9.0",
  "summary": "NFSD: Guard admin state-revocation walks with NFSD_NET_UP"
}