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CVE-2025-71090 (GCVE-0-2025-71090)

Vulnerability from cvelistv5 – Published: 2026-01-13 15:34 – Updated: 2026-08-05 12:11
VLAI
Title
nfsd: fix nfsd_file reference leak in nfsd4_add_rdaccess_to_wrdeleg()
Summary
In the Linux kernel, the following vulnerability has been resolved: nfsd: fix nfsd_file reference leak in nfsd4_add_rdaccess_to_wrdeleg() nfsd4_add_rdaccess_to_wrdeleg() unconditionally overwrites fp->fi_fds[O_RDONLY] with a newly acquired nfsd_file. However, if the client already has a SHARE_ACCESS_READ open from a previous OPEN operation, this action overwrites the existing pointer without releasing its reference, orphaning the previous reference. Additionally, the function originally stored the same nfsd_file pointer in both fp->fi_fds[O_RDONLY] and fp->fi_rdeleg_file with only a single reference. When put_deleg_file() runs, it clears fi_rdeleg_file and calls nfs4_file_put_access() to release the file. However, nfs4_file_put_access() only releases fi_fds[O_RDONLY] when the fi_access[O_RDONLY] counter drops to zero. If another READ open exists on the file, the counter remains elevated and the nfsd_file reference from the delegation is never released. This potentially causes open conflicts on that file. Then, on server shutdown, these leaks cause __nfsd_file_cache_purge() to encounter files with an elevated reference count that cannot be cleaned up, ultimately triggering a BUG() in kmem_cache_destroy() because there are still nfsd_file objects allocated in that cache.
Severity
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: e7a8ebc305f26cab608e59a916a4ae89d6656c5f , < c07dc84ed67c5a182273171639bacbbb87c12175 (git)
Affected: e7a8ebc305f26cab608e59a916a4ae89d6656c5f , < 8072e34e1387d03102b788677d491e2bcceef6f5 (git)
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Linux Linux Affected: 6.17
Unaffected: 0 , < 6.17 (semver)
Unaffected: 6.18.4 , ≤ 6.18.* (semver)
Unaffected: 6.19 , ≤ * (original_commit_for_fix)
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          "product": "Linux",
          "programFiles": [
            "fs/nfsd/nfs4state.c"
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: fix nfsd_file reference leak in nfsd4_add_rdaccess_to_wrdeleg()\n\nnfsd4_add_rdaccess_to_wrdeleg() unconditionally overwrites\nfp-\u003efi_fds[O_RDONLY] with a newly acquired nfsd_file. However, if\nthe client already has a SHARE_ACCESS_READ open from a previous OPEN\noperation, this action overwrites the existing pointer without\nreleasing its reference, orphaning the previous reference.\n\nAdditionally, the function originally stored the same nfsd_file\npointer in both fp-\u003efi_fds[O_RDONLY] and fp-\u003efi_rdeleg_file with\nonly a single reference. When put_deleg_file() runs, it clears\nfi_rdeleg_file and calls nfs4_file_put_access() to release the file.\n\nHowever, nfs4_file_put_access() only releases fi_fds[O_RDONLY] when\nthe fi_access[O_RDONLY] counter drops to zero. If another READ open\nexists on the file, the counter remains elevated and the nfsd_file\nreference from the delegation is never released. This potentially\ncauses open conflicts on that file.\n\nThen, on server shutdown, these leaks cause __nfsd_file_cache_purge()\nto encounter files with an elevated reference count that cannot be\ncleaned up, ultimately triggering a BUG() in kmem_cache_destroy()\nbecause there are still nfsd_file objects allocated in that cache."
        }
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            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
            "version": "3.1"
          },
          "scenarios": [
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              "lang": "en",
              "value": "AV:N - The vulnerable path processes remotely supplied NFSv4.1 COMPOUND OPEN requests through the kernel NFS server. An attacker can trigger it over the network against an exposed NFS export.\nAC:L - The attacker can deterministically retain a READ open using WANT_NO_DELEG and then request an uncontended WRITE-only open that receives a write delegation. No race or condition outside the attacker\u0027s control is required.\nPR:N - A permissive read-write export using AUTH_SYS or AUTH_NULL can allow an unauthenticated client to establish a session and open an anonymous or world-accessible file. No pre-existing target-system privileges are required in this reasonable deployment.\nUI:N - The malicious client alone can issue the OPEN, DELEGRETURN, and CLOSE operations needed to create repeatable leaks. No victim user action is required.\nS:U - The leak and resulting denial of service remain within the NFS server and host kernel security authority. No virtualization, sandbox, or other security boundary is crossed.\nC:N - The bug retains valid nfsd_file objects and does not free, over-read, or expose their contents. It provides no memory-disclosure primitive.\nI:N - The overwritten pointer causes an orphaned reference rather than a dangling pointer or memory corruption. It provides no arbitrary write, control-flow hijack, or data-modification primitive.\nA:H - The leak can be repeated across attacker-accessible files, retaining file-cache objects and causing resource exhaustion or open conflicts. During final nfsd cache teardown, the remaining objects trigger the slab BUG/WARN path and can panic systems configured to treat warnings as fatal."
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        {
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    "datePublished": "2026-01-13T15:34:51.777Z",
    "dateReserved": "2026-01-13T15:30:19.649Z",
    "dateUpdated": "2026-08-05T12:11:59.817Z",
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This potentially\\ncauses open conflicts on that file.\\n\\nThen, on server shutdown, these leaks cause __nfsd_file_cache_purge()\\nto encounter files with an elevated reference count that cannot be\\ncleaned up, ultimately triggering a BUG() in kmem_cache_destroy()\\nbecause there are still nfsd_file objects allocated in that cache.\"},{\"lang\":\"es\",\"value\":\"En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\\n\\nnfsd: corregir fuga de referencia de nfsd_file en nfsd4_add_rdaccess_to_wrdeleg()\\n\\nnfsd4_add_rdaccess_to_wrdeleg() sobrescribe incondicionalmente fp-\u0026gt;fi_fds[O_RDONLY] con un nfsd_file reci\u00e9n adquirido. Sin embargo, si el cliente ya tiene una apertura SHARE_ACCESS_READ de una operaci\u00f3n OPEN anterior, esta acci\u00f3n sobrescribe el puntero existente sin liberar su referencia, dejando hu\u00e9rfana la referencia anterior.\\n\\nAdem\u00e1s, la funci\u00f3n originalmente almacenaba el mismo puntero nfsd_file tanto en fp-\u0026gt;fi_fds[O_RDONLY] como en fp-\u0026gt;fi_rdeleg_file con una sola referencia. Cuando se ejecuta put_deleg_file(), borra fi_rdeleg_file y llama a nfs4_file_put_access() para liberar el archivo.\\n\\nSin embargo, nfs4_file_put_access() solo libera fi_fds[O_RDONLY] cuando el contador fi_access[O_RDONLY] cae a cero. Si existe otra apertura READ en el archivo, el contador permanece elevado y la referencia nfsd_file de la delegaci\u00f3n nunca se libera. 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    "redhat_vex": {
      "aggregate_severity": "Low",
      "current_release_date": "2026-08-14T18:51:26+00:00",
      "cve": "CVE-2025-71090",
      "id": "CVE-2025-71090",
      "initial_release_date": "2025-01-01T00:00:00+00:00",
      "product_status:known_affected": "90",
      "product_status:known_not_affected": "184",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: nfsd: fix nfsd_file reference leak in nfsd4_add_rdaccess_to_wrdeleg()",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-71090.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-08-30T01:41:00Z",
      "cve": "CVE-2025-71090",
      "id": "CVE-2025-71090",
      "initial_release_date": "2026-01-14T00:25:33Z",
      "product_status:known_not_affected": "436",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2025-71090",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2025-71090.json",
      "version": "10"
    }
  }
}



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  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
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