{
  "schema_version": "1.6.1",
  "id": "RPI-CVE-2026-53026",
  "modified": "2026-10-09T11:39:44Z",
  "upstream": [
    "CVE-2026-53026"
  ],
  "published": "2026-06-24T16:31:02Z",
  "summary": "NFSD: fix nfs4_file access extra count in nfsd4_add_rdaccess_to_wrdeleg",
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nNFSD: fix nfs4_file access extra count in nfsd4_add_rdaccess_to_wrdeleg\n\nIn nfsd4_add_rdaccess_to_wrdeleg, if fp->fi_fds[O_RDONLY] is already\nset by another thread, __nfs4_file_get_access should not be called\nto increment the nfs4_file access count since that was already done\nby the thread that added READ access to the file. The extra fi_access\ncount in nfs4_file can prevent the corresponding nfsd_file from being\nfreed.\n\nWhen stopping nfs-server service, these extra access counts trigger a\nBUG in kmem_cache_destroy() that shows nfsd_file object remaining on\n__kmem_cache_shutdown.\n\nThis problem can be reproduced by running the Git project's test\nsuite over NFS.",
  "severity": [
    {
      "type": "CVSS_V3",
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
    }
  ],
  "affected": [
    {
      "package": {
        "ecosystem": "Raspberry Pi OS:13",
        "name": "linux"
      },
      "versions": [
        "1:6.18.29-1+rpt1"
      ],
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "linux-image-6.18.29+rpt-rpi-2712",
            "binary_version": "1:6.18.29-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.18.29+rpt-rpi-v6",
            "binary_version": "1:6.18.29-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.18.29+rpt-rpi-v7",
            "binary_version": "1:6.18.29-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.18.29+rpt-rpi-v8",
            "binary_version": "1:6.18.29-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.18.29+rpt-rpi-v8-rt",
            "binary_version": "1:6.18.29-1+rpt1"
          }
        ]
      },
      "database_specific": {
        "per_version": {
          "1:6.18.29-1+rpt1": {
            "linux_commit": "66318c5b5cd8145a662303af12ed39ac07eb27cc",
            "upstream_version": "6.18.29",
            "assessment": "commit ancestry (strak rule)",
            "upstream_fixed": "6.18.33"
          }
        }
      }
    }
  ],
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-53026"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/4584229395d0d65bd517780afe97ffea07cb2c3d"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/b81572b073441dfd32213e41857676d0dbff4665"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/b48f44f36e6607b2f818560f19deb86b4a9c717b"
    }
  ],
  "database_specific": {
    "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git",
    "upstream_modified": "2026-08-05T13:16:28Z",
    "severity": {
      "source": "kernel CNA",
      "cvss_v3_score": 7.5,
      "cvss_v3_severity": "High",
      "scenario": "AV:N - NFSD is a network-facing NFS server subsystem, and the vulnerable path is reached by remote NFSv4 COMPOUND/OPEN requests over RPC.\nAC:L - A client can drive repeated or concurrent OPEN/write-delegation activity against an exported file; the relevant race/refcount condition is controllable by issuing parallel NFS requests.\nPR:N - In a reasonable NFS deployment using AUTH_SYS/AUTH_NULL-accessible exports, a remote client can reach this path without authenticated target-system privileges.\nUI:N - No victim user action is required; the attacker only sends NFS requests to the server.\nS:U - The impact remains within the vulnerable kernel/NFSD server security authority and does not cross a VM, sandbox, or other separate security boundary.\nC:N - The bug is an extra reference/access count leak, not a use-after-free, out-of-bounds access, or information disclosure primitive.\nI:N - The investigation found no attacker-controlled memory overwrite or data modification primitive; the corruption is limited to over-retaining an internal reference count.\nA:H - The leaked access counts can keep nfsd_file objects pinned and trigger a kmem_cache_destroy BUG during NFSD shutdown; repeated triggering can deny service through persistent kernel resource leakage."
    }
  }
}