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

Type: advisorySources: OSV

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.

Products
Kernel
Affected versions
Not specified
Fixed versions
5.10.253, 6.1.167, 6.12.78, 6.18.20, 6.19.10, 6.6.130
CVEs
CVE-2026-31403
Confirmed fixed CVEs
Not specified
Updated in this feed
3 Nov 2026, 01:24 UTC · Revision 1

Source evidence

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

core-osv · Original source

Published 3 Apr 2026, 15:16 UTC

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.

osv:CVE-2026-31403

Kernel

Fixed versions: 5.10.253, 6.1.167, 6.6.130, 6.12.78, 6.18.20, 6.19.10

Complete source record
{
  "id": "a5db6dfd03bb25587367d5338af1396aa0f33f4aa1e166c796ac2cf6881c2fcf",
  "url": "https://osv.dev/vulnerability/CVE-2026-31403",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "NFSD: Hold net reference for the lifetime of /proc/fs/nfs/exports fd",
    "summary": "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.",
    "evidence": "osv:CVE-2026-31403",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
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            "value": "5.10.253",
            "evidence": "/affected/1/ranges"
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            "evidence": "/affected/1/ranges"
          },
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            "evidence": "/affected/1/ranges"
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            "evidence": "/affected/1/ranges"
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          {
            "value": "6.18.20",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.19.10",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "high",
    "structured": {
      "id": "CVE-2026-31403",
      "aliases": [
        "CVE-2026-31403"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"
        }
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      "affected": [
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                {
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        {
          "ranges": [
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              "type": "ECOSYSTEM",
              "events": [
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                  "introduced": "3.9.0"
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                  "fixed": "5.10.253"
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            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "5.11.0"
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                {
                  "fixed": "6.1.167"
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              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.2.0"
                },
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            {
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            {
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            {
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          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
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          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-31403.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:24.810968534Z",
      "provider": "osv",
      "references": [
        "https://cert-portal.siemens.com/productcert/html/ssa-019113.html",
        "https://cert-portal.siemens.com/productcert/html/ssa-082556.html",
        "https://cert-portal.siemens.com/productcert/html/ssa-457936.html",
        "https://git.kernel.org/stable/c/6a8d70e2ad6aad2c345a5048edcb8168036f97d6",
        "https://git.kernel.org/stable/c/76740c28050dc6db2f5550f1325b00a11bbb3255",
        "https://git.kernel.org/stable/c/c7f406fb341d6747634b8b1fa5461656e5e56076",
        "https://git.kernel.org/stable/c/d1a19217995df9c7e4118f5a2820c5032fef2945",
        "https://git.kernel.org/stable/c/db4a9f99b12a7ee1c19d86c83a3b752c7effa6c6",
        "https://git.kernel.org/stable/c/e3d77f935639e6ae4b381c80464c31df998d61f4",
        "https://git.kernel.org/stable/c/e7fcf179b82d3a3730fd8615da01b087cc654d0b",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/31xxx/CVE-2026-31403.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-31403",
        "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
      ],
      "provider_metadata": {
        "cna_assigner": "Linux",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/31xxx/CVE-2026-31403.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-31403",
        "evidence": "/id"
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    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 491584,
  "published_at": "2026-04-03T15:16:06.444+00:00"
}