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GHSA-85M5-F4F3-Q6F5

Vulnerability from github – Published: 2026-04-03 18:31 – Updated: 2026-07-14 15:31
VLAI
Details

In the Linux kernel, the following vulnerability has been resolved:

NFSD: Hold net reference for the lifetime of /proc/fs/nfs/exports fd

The /proc/fs/nfs/exports proc entry is created at module init and persists for the module's lifetime. exports_proc_open() captures the caller's current network namespace and stores its svc_export_cache in seq->private, but takes no reference on the namespace. If the namespace is subsequently torn down (e.g. container destruction after the opener does setns() to a different namespace), nfsd_net_exit() calls nfsd_export_shutdown() which frees the cache. Subsequent reads on the still-open fd dereference the freed cache_detail, walking a freed hash table.

Hold a reference on the struct net for the lifetime of the open file descriptor. This prevents nfsd_net_exit() from running -- and thus prevents nfsd_export_shutdown() from freeing the cache -- while any exports fd is open. cache_detail already stores its net pointer (cd->net, set by cache_create_net()), so exports_release() can retrieve it without additional per-file storage.

Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
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{
  "affected": [],
  "aliases": [
    "CVE-2026-31403"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-04-03T16:16:39Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nNFSD: Hold net reference for the lifetime of /proc/fs/nfs/exports fd\n\nThe /proc/fs/nfs/exports proc entry is created at module init\nand persists for the module\u0027s lifetime. exports_proc_open()\ncaptures the caller\u0027s current network namespace and stores\nits svc_export_cache in seq-\u003eprivate, but takes no reference\non the namespace. If the namespace is subsequently torn down\n(e.g. container destruction after the opener does setns() to a\ndifferent namespace), nfsd_net_exit() calls nfsd_export_shutdown()\nwhich frees the cache. Subsequent reads on the still-open fd\ndereference the freed cache_detail, walking a freed hash table.\n\nHold a reference on the struct net for the lifetime of the open\nfile descriptor. This prevents nfsd_net_exit() from running --\nand thus prevents nfsd_export_shutdown() from freeing the cache\n-- while any exports fd is open. cache_detail already stores\nits net pointer (cd-\u003enet, set by cache_create_net()), so\nexports_release() can retrieve it without additional per-file\nstorage.",
  "id": "GHSA-85m5-f4f3-q6f5",
  "modified": "2026-07-14T15:31:49Z",
  "published": "2026-04-03T18:31:23Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-31403"
    },
    {
      "type": "WEB",
      "url": "https://cert-portal.siemens.com/productcert/html/ssa-019113.html"
    },
    {
      "type": "WEB",
      "url": "https://cert-portal.siemens.com/productcert/html/ssa-082556.html"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/6a8d70e2ad6aad2c345a5048edcb8168036f97d6"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/76740c28050dc6db2f5550f1325b00a11bbb3255"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/c7f406fb341d6747634b8b1fa5461656e5e56076"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/d1a19217995df9c7e4118f5a2820c5032fef2945"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/db4a9f99b12a7ee1c19d86c83a3b752c7effa6c6"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/e3d77f935639e6ae4b381c80464c31df998d61f4"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/e7fcf179b82d3a3730fd8615da01b087cc654d0b"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}



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