CVE-2023-53606 (GCVE-0-2023-53606)

Vulnerability from cvelistv5 – Published: 2025-10-04 15:44 – Updated: 2026-10-15 21:41
VLAI
Title
nfsd: clean up potential nfsd_file refcount leaks in COPY codepath
Summary
In the Linux kernel, the following vulnerability has been resolved: nfsd: clean up potential nfsd_file refcount leaks in COPY codepath There are two different flavors of the nfsd4_copy struct. One is embedded in the compound and is used directly in synchronous copies. The other is dynamically allocated, refcounted and tracked in the client struture. For the embedded one, the cleanup just involves releasing any nfsd_files held on its behalf. For the async one, the cleanup is a bit more involved, and we need to dequeue it from lists, unhash it, etc. There is at least one potential refcount leak in this code now. If the kthread_create call fails, then both the src and dst nfsd_files in the original nfsd4_copy object are leaked. The cleanup in this codepath is also sort of weird. In the async copy case, we'll have up to four nfsd_file references (src and dst for both flavors of copy structure). They are both put at the end of nfsd4_do_async_copy, even though the ones held on behalf of the embedded one outlive that structure. Change it so that we always clean up the nfsd_file refs held by the embedded copy structure before nfsd4_copy returns. Rework cleanup_async_copy to handle both inter and intra copies. Eliminate nfsd4_cleanup_intra_ssc since it now becomes a no-op.
Severity
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
SSVC
Exploitation: none Automatable: yes Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-10-15 21:35 UTC
Assigner
Linux CNA under the mitre root
CNA scorecard D 53/100 over 7033 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: e0639dc5805a9d4faaa2c07ad98fa853b9529dd3 , < fd63299db8090307eae66f2aef17c8f00aafa0a9 (git)
Affected: e0639dc5805a9d4faaa2c07ad98fa853b9529dd3 , < b3169b6ffe036b549c296a9e71591d29a1fb3209 (git)
Affected: e0639dc5805a9d4faaa2c07ad98fa853b9529dd3 , < 75b8c681c563ef7e85da6862354efc18d2a08b1b (git)
Affected: e0639dc5805a9d4faaa2c07ad98fa853b9529dd3 , < 8f565846fbe8182961498d4cbe618b15076a683b (git)
Affected: e0639dc5805a9d4faaa2c07ad98fa853b9529dd3 , < 6ba434cb1a8d403ea9aad1b667c3ea3ad8b3191f (git)
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Linux Linux Affected: 4.20
Unaffected: 0 , < 4.20 (semver)
Unaffected: 5.10.220 , ≤ 5.10.* (semver)
Unaffected: 5.15.154 , ≤ 5.15.* (semver)
Unaffected: 6.1.16 , ≤ 6.1.* (semver)
Unaffected: 6.2.3 , ≤ 6.2.* (semver)
Unaffected: 6.3 , ≤ * (original_commit_for_fix)
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      "cve": "CVE-2023-53606",
      "id": "CVE-2023-53606",
      "initial_release_date": "2023-01-01T00:00:00+00:00",
      "product_status:fixed": "201",
      "product_status:known_affected": "112",
      "product_status:known_not_affected": "76",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: nfsd: clean up potential nfsd_file refcount leaks in COPY codepath",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2023/cve-2023-53606.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-10-16T13:22:47Z",
      "cve": "CVE-2023-53606",
      "id": "CVE-2023-53606",
      "initial_release_date": "2025-10-05T02:55:31Z",
      "product_status:known_affected": "0",
      "product_status:known_not_affected": "520",
      "product_status:recommended": "54",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2023-53606",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/2025/cve-2023-53606.json",
      "version": "13"
    },
    "vulnrichment": {
      "containers": {
        "adp": [
          {
            "metrics": [
              {
                "other": {
                  "content": {
                    "id": "CVE-2023-53606",
                    "options": [
                      {
                        "Exploitation": "none"
                      },
                      {
                        "Automatable": "yes"
                      },
                      {
                        "Technical Impact": "partial"
                      }
                    ],
                    "role": "CISA Coordinator",
                    "timestamp": "2026-10-15T21:35:51.806185Z",
                    "version": "2.0.3"
                  },
                  "type": "ssvc"
                }
              }
            ],
            "providerMetadata": {
              "dateUpdated": "2026-10-15T21:35:52.282Z",
              "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
              "shortName": "CISA-ADP"
            },
            "title": "CISA ADP Vulnrichment"
          }
        ],
        "cna": {
          "affected": [
            {
              "defaultStatus": "unaffected",
              "product": "Linux",
              "programFiles": [
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              ],
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "vendor": "Linux",
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                  "versionType": "git"
                },
                {
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                  "status": "affected",
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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": [
                {
                  "status": "affected",
                  "version": "4.20"
                },
                {
                  "lessThan": "4.20",
                  "status": "unaffected",
                  "version": "0",
                  "versionType": "semver"
                },
                {
                  "lessThanOrEqual": "5.10.*",
                  "status": "unaffected",
                  "version": "5.10.220",
                  "versionType": "semver"
                },
                {
                  "lessThanOrEqual": "5.15.*",
                  "status": "unaffected",
                  "version": "5.15.154",
                  "versionType": "semver"
                },
                {
                  "lessThanOrEqual": "6.1.*",
                  "status": "unaffected",
                  "version": "6.1.16",
                  "versionType": "semver"
                },
                {
                  "lessThanOrEqual": "6.2.*",
                  "status": "unaffected",
                  "version": "6.2.3",
                  "versionType": "semver"
                },
                {
                  "lessThanOrEqual": "*",
                  "status": "unaffected",
                  "version": "6.3",
                  "versionType": "original_commit_for_fix"
                }
              ]
            }
          ],
          "cpeApplicability": [
            {
              "nodes": [
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                  "cpeMatch": [
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                      "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                      "versionEndExcluding": "5.10.220",
                      "versionStartIncluding": "4.20",
                      "vulnerable": true
                    },
                    {
                      "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                      "versionEndExcluding": "5.15.154",
                      "versionStartIncluding": "4.20",
                      "vulnerable": true
                    },
                    {
                      "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                      "versionEndExcluding": "6.1.16",
                      "versionStartIncluding": "4.20",
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                  "negate": false,
                  "operator": "OR"
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          ],
          "descriptions": [
            {
              "lang": "en",
              "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: clean up potential nfsd_file refcount leaks in COPY codepath\n\nThere are two different flavors of the nfsd4_copy struct. One is\nembedded in the compound and is used directly in synchronous copies. The\nother is dynamically allocated, refcounted and tracked in the client\nstruture. For the embedded one, the cleanup just involves releasing any\nnfsd_files held on its behalf. For the async one, the cleanup is a bit\nmore involved, and we need to dequeue it from lists, unhash it, etc.\n\nThere is at least one potential refcount leak in this code now. If the\nkthread_create call fails, then both the src and dst nfsd_files in the\noriginal nfsd4_copy object are leaked.\n\nThe cleanup in this codepath is also sort of weird. In the async copy\ncase, we\u0027ll have up to four nfsd_file references (src and dst for both\nflavors of copy structure). They are both put at the end of\nnfsd4_do_async_copy, even though the ones held on behalf of the embedded\none outlive that structure.\n\nChange it so that we always clean up the nfsd_file refs held by the\nembedded copy structure before nfsd4_copy returns. Rework\ncleanup_async_copy to handle both inter and intra copies. Eliminate\nnfsd4_cleanup_intra_ssc since it now becomes a no-op."
            }
          ],
          "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 vulnerable code is `nfsd4_copy()`, the in-kernel NFS server\u0027s handler for the NFSv4.2 COPY operation, reached entirely by processing a compound RPC received on TCP port 2049 from a remote client. No local access to the server is needed.\nAC:L - The attacker manufactures the trigger: affected kernels place no cap on concurrent async COPYs, so flooding the server with async COPY requests (each spawning a kthread) drives `kthread_create()` into failure and leaks refs, and with inter-server copy enabled a bogus source filehandle makes `nfs42_ssc_open()` fail on every single request for a fully deterministic per-request leak.\nPR:N - With AUTH_SYS \u2014 the default for essentially all NFS deployments \u2014 the server performs no credential verification; EXCHANGE_ID, CREATE_SESSION and OPEN succeed for any host permitted by the export list with no secret of any kind, so the attacker holds no server-verified privileges prior to the attack.\nUI:N - The attacker issues the COPY compounds directly from its own NFS client; no action by any administrator or other user on the server is required.\nS:U - The leaked `nfsd_file`/`struct file`/inode references are kernel objects consumed within the same kernel security authority; no VM, IOMMU, or sandbox boundary is crossed.\nC:N - A reference-count leak neither reads out-of-bounds memory nor exposes kernel data to the client; the COPY reply is unchanged and no uninitialized or freed memory is disclosed.\nI:N - Nothing is written out of bounds and no kernel object is corrupted \u2014 the refcount merely stays too high, so no file data, metadata, or kernel state is modified beyond the accounting itself.\nA:H - Every leaked reference permanently pins an `nfsd_file`, `struct file`, inode, dentry and page cache that the filecache GC/LRU can never reclaim, and the leak is repeatable without bound by a remote client, so kernel memory is exhausted into OOM and the export becomes permanently unmountable; the leak also accelerates under the very memory pressure it causes, making it unrecoverable without reboot."
                }
              ]
            }
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            "dateUpdated": "2026-08-05T09:15:05.102Z",
            "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "shortName": "Linux"
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          "references": [
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              "url": "https://git.kernel.org/stable/c/fd63299db8090307eae66f2aef17c8f00aafa0a9"
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              "url": "https://git.kernel.org/stable/c/b3169b6ffe036b549c296a9e71591d29a1fb3209"
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            {
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            },
            {
              "url": "https://git.kernel.org/stable/c/8f565846fbe8182961498d4cbe618b15076a683b"
            },
            {
              "url": "https://git.kernel.org/stable/c/6ba434cb1a8d403ea9aad1b667c3ea3ad8b3191f"
            }
          ],
          "title": "nfsd: clean up potential nfsd_file refcount leaks in COPY codepath",
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            "engine": "bippy-1.2.0"
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      "cveMetadata": {
        "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "assignerShortName": "Linux",
        "cveId": "CVE-2023-53606",
        "datePublished": "2025-10-04T15:44:15.908Z",
        "dateReserved": "2025-10-04T15:40:38.480Z",
        "dateUpdated": "2026-10-15T21:41:31.680Z",
        "state": "PUBLISHED"
      },
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}



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Sightings

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Vulnerability timeline

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