{
  "affected": [
    {
      "ranges": [
        {
          "events": [
            {
              "introduced": "030d794bf49855f5e2a9e8dfbfad34211d1eb08b"
            },
            {
              "fixed": "159a4fab7170badd6c4a553aef81cac079d6f4ee"
            },
            {
              "fixed": "b3526ae3351968f6726bcbe25d8d09973ad79109"
            },
            {
              "fixed": "7f5bcdc8da15077ebe846c2756a5a17741021410"
            },
            {
              "fixed": "89c8e0733e8c46b7973503f15b1b31a8587d8030"
            },
            {
              "fixed": "f15b87521168c2a92cb1931f532cba422f856f01"
            },
            {
              "fixed": "edeefb111d6181a4aa278f415b005efe284b9489"
            },
            {
              "fixed": "3f019571928b269feebcff59926ec13294215e0e"
            },
            {
              "fixed": "5ce1ed6159731a41fdd0b03eedbed4e147036a5a"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Linux",
        "name": "Kernel"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "3.10.0"
            },
            {
              "fixed": "5.10.270"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "5.11.0"
            },
            {
              "fixed": "5.15.221"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "5.16.0"
            },
            {
              "fixed": "6.1.188"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.2.0"
            },
            {
              "fixed": "6.6.157"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.7.0"
            },
            {
              "fixed": "6.12.109"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.13.0"
            },
            {
              "fixed": "6.18.50"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.19.0"
            },
            {
              "fixed": "7.2.4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "database_specific": {
    "cna_assigner": "Linux",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89540.json"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nsunrpc: init gssp_lock before publishing proc entry\n\ncreate_use_gss_proxy_proc_entry() publishes /proc/net/rpc/use-gss-proxy\nvia proc_create_data() before init_gssp_clnt() runs mutex_init() on\nsn-\u003egssp_lock.  Once the dentry is linked under proc_subdir_lock it is\nimmediately reachable from userspace, so a write that lands in the\nwindow drives set_gssp_clnt() into mutex_lock() on a zero-initialized\nstruct mutex.\n\n    create_use_gss_proxy_proc_entry(net)\n      proc_create_data(\"use-gss-proxy\", ...)   /* dentry live */\n      init_gssp_clnt(sn)\n        mutex_init(\u0026sn-\u003egssp_lock)             /* too late */\n\n    write_gssp()\n      set_gssp_clnt(net)\n        mutex_lock(\u0026sn-\u003egssp_lock)             /* uninitialized */\n        gssp_rpc_create(...)\n        sn-\u003egssp_clnt = clnt\n        mutex_unlock(\u0026sn-\u003egssp_lock)\n\nThe window spans only the two statements between proc_create_data()\nreturning and init_gssp_clnt(), so a writer reaches it only if the\nregistering thread is preempted there while another task is already\nopening the freshly published file.  register_pernet_subsys() runs in\npreemptible context under pernet_ops_rwsem, so that preemption is\npossible, and the window widens on auth_rpcgss module load, when the\nproc entry is created for every live net namespace whose tasks are\nalready running.  A writer that wins the race locks a zero-filled\nstruct mutex.  On CONFIG_DEBUG_MUTEXES the missing magic value trips a\n\"lock used without init\" splat; on a production kernel the fast path\nacquires the lock via CMPXCHG(owner, 0, current).  In the latter case\na second writer that arrives before init_gssp_clnt() re-zeroes owner\ncan enter set_gssp_clnt() concurrently, shut down the first writer's\nclnt while it is still in use, and leak the loser's clnt.\n\nFix by initializing sn-\u003egssp_lock in sunrpc_init_net() so its lifetime\nmatches the sunrpc_net it lives in.  sn-\u003egssp_clnt is already NULL from\nthe kzalloc that backs net_generic storage, so the lazy helper is no\nlonger needed; drop init_gssp_clnt(), its prototype, and the call from\ncreate_use_gss_proxy_proc_entry().  sunrpc.ko is a build-time\ndependency of auth_rpcgss.ko, so sunrpc_init_net() has always run on\nevery netns before any auth_gss pernet init can publish the proc\nentry.",
  "id": "CVE-2026-89540",
  "modified": "2026-09-15T03:31:08.094331990Z",
  "published": "2026-09-11T19:44:17.440Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/159a4fab7170badd6c4a553aef81cac079d6f4ee"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/3f019571928b269feebcff59926ec13294215e0e"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/5ce1ed6159731a41fdd0b03eedbed4e147036a5a"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/7f5bcdc8da15077ebe846c2756a5a17741021410"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/89c8e0733e8c46b7973503f15b1b31a8587d8030"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/b3526ae3351968f6726bcbe25d8d09973ad79109"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/edeefb111d6181a4aa278f415b005efe284b9489"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f15b87521168c2a92cb1931f532cba422f856f01"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89540.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-89540"
    },
    {
      "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": "sunrpc: init gssp_lock before publishing proc entry"
}