Vulnerability-Lookup

FKIE_CVE-2026-53396

Vulnerability from fkie_nvd - Published: 2026-07-19 12:16 - Updated: 2026-08-17 05:17

Severity

7.1 (High) - CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:H

Summary

In the Linux kernel, the following vulnerability has been resolved: nfsd: fix posix_acl leak and ignored error in nfsd4_create_file nfsd4_create_file() has two bugs in its ACL handling: The return value of nfsd4_acl_to_attr() is silently discarded. When the NFSv4-to-POSIX ACL conversion fails (e.g., -EINVAL for unsupported ACE types), the file is created without any ACL and the client receives NFS4_OK. This violates RFC 7530/8881 which require the server to reject unsupported attributes on CREATE. When start_creating() fails after ACL attributes have been populated in attrs (either via nfsd4_acl_to_attr or via ownership transfer from open->op_dpacl/op_pacl), the function jumps to out_write which skips nfsd_attrs_free(). The posix_acl allocations are leaked. A client can trigger this repeatedly with OPEN(CREATE), ACL attributes, and an invalid filename (e.g., longer than NAME_MAX). Fix both by capturing the nfsd4_acl_to_attr() return value and by changing the early error paths to jump to out instead of out_write. Initialize child to ERR_PTR(-EINVAL) so that end_creating() is safe to call even if start_creating() was never reached.

References

	URL	Tags
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/18cf006a08babec0bbac2a3784f8f28e56e47490	Patch
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/24c975bbdd564d7d0ad90294bfa69729830345de	Patch

Impacted products

	Vendor	Product	Version
	linux	linux_kernel	*

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/nfsd/nfs4proc.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "18cf006a08babec0bbac2a3784f8f28e56e47490",
              "status": "affected",
              "version": "7ab96df840e60eb933abfe65fc5fe44e72f16dc0",
              "versionType": "git"
            },
            {
              "lessThan": "24c975bbdd564d7d0ad90294bfa69729830345de",
              "status": "affected",
              "version": "7ab96df840e60eb933abfe65fc5fe44e72f16dc0",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/nfsd/nfs4proc.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.19"
            },
            {
              "lessThan": "6.19",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.3",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
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              "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "9526B150-E2B3-4C6F-8AE5-1AF92B75AD9E",
              "versionEndExcluding": "7.1.3",
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              "vulnerable": true
            }
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          "operator": "OR"
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    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: fix posix_acl leak and ignored error in nfsd4_create_file\n\nnfsd4_create_file() has two bugs in its ACL handling:\n\nThe return value of nfsd4_acl_to_attr() is silently discarded.  When\nthe NFSv4-to-POSIX ACL conversion fails (e.g., -EINVAL for\nunsupported ACE types), the file is created without any ACL and the\nclient receives NFS4_OK.  This violates RFC 7530/8881 which require\nthe server to reject unsupported attributes on CREATE.\n\nWhen start_creating() fails after ACL attributes have been populated\nin attrs (either via nfsd4_acl_to_attr or via ownership transfer from\nopen-\u003eop_dpacl/op_pacl), the function jumps to out_write which skips\nnfsd_attrs_free().  The posix_acl allocations are leaked.  A client\ncan trigger this repeatedly with OPEN(CREATE), ACL attributes, and an\ninvalid filename (e.g., longer than NAME_MAX).\n\nFix both by capturing the nfsd4_acl_to_attr() return value and by\nchanging the early error paths to jump to out instead of out_write.\nInitialize child to ERR_PTR(-EINVAL) so that end_creating() is safe\nto call even if start_creating() was never reached."
    }
  ],
  "id": "CVE-2026-53396",
  "lastModified": "2026-08-17T05:17:14.153",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 7.1,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "NONE",
          "integrityImpact": "LOW",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 2.8,
        "impactScore": 4.2,
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-07-19T12:16:50.693",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/18cf006a08babec0bbac2a3784f8f28e56e47490"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/24c975bbdd564d7d0ad90294bfa69729830345de"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-401"
        }
      ],
      "source": "nvd@nist.gov",
      "type": "Primary"
    }
  ]
}

CVE-2026-53396 (GCVE-0-2026-53396)

Vulnerability from cvelistv5 – Published: 2026-07-19 12:01 – Updated: 2026-08-17 04:50

Title

nfsd: fix posix_acl leak and ignored error in nfsd4_create_file

Summary

Severity

7.1 (High)


                        
                          CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:H

Assigner

Linux CNA under the mitre root

CNA scorecard D 53/100 over 6992 records in the last 180 days details

References

2 references

URL	Tags
https://git.kernel.org/stable/c/18cf006a08babec0b…
https://git.kernel.org/stable/c/24c975bbdd564d7d0…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 7ab96df840e60eb933abfe65fc5fe44e72f16dc0 , < 18cf006a08babec0bbac2a3784f8f28e56e47490 (git) Affected: 7ab96df840e60eb933abfe65fc5fe44e72f16dc0 , < 24c975bbdd564d7d0ad90294bfa69729830345de (git)
Linux	Linux	Affected: 6.19 Unaffected: 0 , < 6.19 (semver) Unaffected: 7.1.3 , ≤ 7.1.* (semver) Unaffected: 7.2 , ≤ * (original_commit_for_fix)

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/nfsd/nfs4proc.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "18cf006a08babec0bbac2a3784f8f28e56e47490",
              "status": "affected",
              "version": "7ab96df840e60eb933abfe65fc5fe44e72f16dc0",
              "versionType": "git"
            },
            {
              "lessThan": "24c975bbdd564d7d0ad90294bfa69729830345de",
              "status": "affected",
              "version": "7ab96df840e60eb933abfe65fc5fe44e72f16dc0",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/nfsd/nfs4proc.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.19"
            },
            {
              "lessThan": "6.19",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.3",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.1.3",
                  "versionStartIncluding": "6.19",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2",
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                }
              ],
              "negate": false,
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      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: fix posix_acl leak and ignored error in nfsd4_create_file\n\nnfsd4_create_file() has two bugs in its ACL handling:\n\nThe return value of nfsd4_acl_to_attr() is silently discarded.  When\nthe NFSv4-to-POSIX ACL conversion fails (e.g., -EINVAL for\nunsupported ACE types), the file is created without any ACL and the\nclient receives NFS4_OK.  This violates RFC 7530/8881 which require\nthe server to reject unsupported attributes on CREATE.\n\nWhen start_creating() fails after ACL attributes have been populated\nin attrs (either via nfsd4_acl_to_attr or via ownership transfer from\nopen-\u003eop_dpacl/op_pacl), the function jumps to out_write which skips\nnfsd_attrs_free().  The posix_acl allocations are leaked.  A client\ncan trigger this repeatedly with OPEN(CREATE), ACL attributes, and an\ninvalid filename (e.g., longer than NAME_MAX).\n\nFix both by capturing the nfsd4_acl_to_attr() return value and by\nchanging the early error paths to jump to out instead of out_write.\nInitialize child to ERR_PTR(-EINVAL) so that end_creating() is safe\nto call even if start_creating() was never reached."
        }
      ],
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            "baseSeverity": "HIGH",
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            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - The vulnerable code is reached via NFSv4 OPEN(CREATE) handled by nfsd over the network (RPC on TCP/2049), from nfsd4_proc_compound() through nfsd4_open() and do_open_lookup() into nfsd4_create_file().\nAC:L - An authenticated NFS client can reliably trigger the leak by sending OPEN(CREATE) with ACL attributes and a filename that causes start_creating() to fail (e.g., longer than the backing filesystem NAME_MAX); no race or attacker-uncontrollable conditions are required.\nPR:L - Exploitation requires an authenticated NFS client with write/create permission on the target export directory (enforced by fh_verify()/nfsd_permission), which maps to basic authorized-user access rather than unauthenticated or server-admin privileges.\nUI:N - No victim interaction is needed beyond the attacker sending crafted NFSv4 compound requests to the server.\nS:U - Impact is confined to kernel memory management and exported file metadata within the NFS server\u0027s security authority; it does not cross VM, container, or IOMMU boundaries.\nC:N - The bug is a refcount leak of posix_acl kernel objects with no out-of-bounds read, use-after-free, or other mechanism that exposes kernel memory to the attacker.\nI:L - The ignored nfsd4_acl_to_attr() error allows files to be created without the requested ACL while returning NFS4_OK, causing limited but incorrect modification of exported file security attributes on shared storage.\nA:H - Repeated triggering leaks unbounded posix_acl slab objects per request, enabling sustained kernel memory exhaustion that can deny NFS service and degrade overall system availability."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-17T04:50:48.148Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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        },
        {
          "url": "https://git.kernel.org/stable/c/24c975bbdd564d7d0ad90294bfa69729830345de"
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-53396",
    "datePublished": "2026-07-19T12:01:58.375Z",
    "dateReserved": "2026-06-09T07:44:35.402Z",
    "dateUpdated": "2026-08-17T04:50:48.148Z",
    "state": "PUBLISHED"
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  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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