CVE-2026-53394 (GCVE-0-2026-53394)
Vulnerability from cvelistv5
Published
2026-07-19 12:01
Modified
2026-08-17 04:50
Severity ?
7.5 (High) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: nfsd: avoid leaking pre-allocated openowner on unconfirmed retry race When find_or_alloc_open_stateowner() encounters an unconfirmed owner, it calls release_openowner() and sets oo = NULL. Control then falls through past the `if (oo)` guard -- which would have freed any pre-allocated `new` -- and unconditionally executes `new = alloc_stateowner(...)`. If `new` was already allocated on a prior iteration, the pointer is silently overwritten and the previous allocation (slab object + owner name buffer) is leaked. This requires a race: two NFSv4.0 OPEN threads with the same owner string, where a concurrent thread inserts a new unconfirmed owner into the hash between retry iterations. The window is narrow but repeatable under adversarial conditions. Fix by adding `goto retry` after `oo = NULL` so the already-allocated `new` is reused on the next iteration rather than overwritten.
References
Impacted products
Vendor Product Version
Linux Linux Version: 23df17788c6212809848f836b10c4f85b16843a5
Version: 23df17788c6212809848f836b10c4f85b16843a5
Version: 23df17788c6212809848f836b10c4f85b16843a5
Version: 23df17788c6212809848f836b10c4f85b16843a5
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/nfsd/nfs4state.c"
          ],
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        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
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          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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              "version": "6.10"
            },
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              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
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              "status": "unaffected",
              "version": "6.12.95",
              "versionType": "semver"
            },
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              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.38",
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            },
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              "version": "7.1.3",
              "versionType": "semver"
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            {
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              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
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                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                  "vulnerable": true
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                  "versionEndExcluding": "7.2",
                  "versionStartIncluding": "6.10",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: avoid leaking pre-allocated openowner on unconfirmed retry race\n\nWhen find_or_alloc_open_stateowner() encounters an unconfirmed owner, it\ncalls release_openowner() and sets oo = NULL. Control then falls through\npast the `if (oo)` guard -- which would have freed any pre-allocated\n`new` -- and unconditionally executes `new = alloc_stateowner(...)`. If\n`new` was already allocated on a prior iteration, the pointer is\nsilently overwritten and the previous allocation (slab object + owner\nname buffer) is leaked.\n\nThis requires a race: two NFSv4.0 OPEN threads with the same owner\nstring, where a concurrent thread inserts a new unconfirmed owner into\nthe hash between retry iterations. The window is narrow but repeatable\nunder adversarial conditions.\n\nFix by adding `goto retry` after `oo = NULL` so the already-allocated\n`new` is reused on the next iteration rather than overwritten."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.5,
            "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": [
            {
              "lang": "en",
              "value": "AV:N - The flaw is in nfsd\u0027s NFSv4 OPEN handling, reachable remotely via NFS RPC on TCP/UDP port 2049 through svc_recv \u2192 NFSPROC4_COMPOUND \u2192 nfsd4_open \u2192 nfsd4_process_open1 \u2192 find_or_alloc_open_stateowner().\nAC:L - Exploitation requires a race between two NFSv4.0 OPEN requests with the same owner string, but the attacker controls both sides by issuing concurrent compounds from multiple connections; the fix commit itself states this is repeatable under adversarial conditions.\nPR:N - No local privileges on the server are required\u2014only remote NFSv4 client access to establish a clientid (SETCLIENTID/CONFIRM) and send concurrent OPEN operations; the leak occurs in nfsd4_process_open1 before export/file permission checks complete.\nUI:N - Exploitation is fully automated via concurrent NFS protocol requests and requires no action from any victim user on the server or client side.\nS:U - Impact is confined to kernel memory consumption within nfsd\u0027s security authority; there is no cross-boundary escape to other components or privilege domains.\nC:N - This is a pure memory leak where orphaned slab objects lose all kernel references; no out-of-bounds read, use-after-free, or other mechanism exposes kernel data to the attacker.\nI:N - The bug silently drops a pointer to an allocated object without corrupting adjacent memory or providing any write or control-flow primitive\u2014only heap memory is lost.\nA:H - Each successful race leaks a slab object plus an attacker-controlled owner-name buffer (up to NFS4_OPAQUE_LIMIT bytes), and the attack can be repeated indefinitely to cause unbounded kernel memory exhaustion, denying NFS service and potentially triggering system-wide OOM conditions."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-17T04:50:45.946Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/c9aefb2b5f11337c9202c5bd0c45d71198449718"
        },
        {
          "url": "https://git.kernel.org/stable/c/017a6150106b054cc84d1b0582d97bd3a74d4281"
        },
        {
          "url": "https://git.kernel.org/stable/c/a10bf67fe06469a71a401f72f328237345d553c0"
        },
        {
          "url": "https://git.kernel.org/stable/c/57aee7a35bb12753057c5b65d72d1f46c0e95b07"
        }
      ],
      "title": "nfsd: avoid leaking pre-allocated openowner on unconfirmed retry race",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-53394",
    "datePublished": "2026-07-19T12:01:57.261Z",
    "dateReserved": "2026-06-09T07:44:35.402Z",
    "dateUpdated": "2026-08-17T04:50:45.946Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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