Vulnerability-Lookup

GHSA-HMPX-QPGP-FW83

Vulnerability from github – Published: 2026-07-19 12:30 – Updated: 2026-07-20 15:31

Details

In the Linux kernel, the following vulnerability has been resolved:

nfsd: fix dead ACL conflict guard in nfsd4_create

nfsd4_create() steals create->cr_dpacl/cr_pacl into the local nfsd_attrs via the designated initializer, then immediately sets the source pointers to NULL. The subsequent conflict guard tests the already-nilled source fields, making it permanently dead code:

if (create->cr_acl) {
    if (create->cr_dpacl || create->cr_pacl)  /* always false */

When a client encodes both FATTR4_WORD0_ACL and FATTR4_WORD2_POSIX_{DEFAULT,ACCESS}_ACL in the same CREATE fattr bitmap, nfsd4_acl_to_attr() overwrites attrs.na_pacl/na_dpacl without releasing the originals, leaking two posix_acl slab objects per request. Repeated requests cause unbounded slab exhaustion.

Fix by checking attrs.na_dpacl/na_pacl (the stolen values) instead of the nilled create->cr_dpacl/cr_pacl, matching the correct pattern already used in nfsd4_setattr().

Severity

7.5 (High)


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

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{
  "affected": [],
  "aliases": [
    "CVE-2026-53395"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-674"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-07-19T12:16:50Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: fix dead ACL conflict guard in nfsd4_create\n\nnfsd4_create() steals create-\u003ecr_dpacl/cr_pacl into the local\nnfsd_attrs via the designated initializer, then immediately sets the\nsource pointers to NULL. The subsequent conflict guard tests the\nalready-nilled source fields, making it permanently dead code:\n\n    if (create-\u003ecr_acl) {\n        if (create-\u003ecr_dpacl || create-\u003ecr_pacl)  /* always false */\n\nWhen a client encodes both FATTR4_WORD0_ACL and\nFATTR4_WORD2_POSIX_{DEFAULT,ACCESS}_ACL in the same CREATE fattr\nbitmap, nfsd4_acl_to_attr() overwrites attrs.na_pacl/na_dpacl without\nreleasing the originals, leaking two posix_acl slab objects per\nrequest. Repeated requests cause unbounded slab exhaustion.\n\nFix by checking attrs.na_dpacl/na_pacl (the stolen values) instead of\nthe nilled create-\u003ecr_dpacl/cr_pacl, matching the correct pattern\nalready used in nfsd4_setattr().",
  "id": "GHSA-hmpx-qpgp-fw83",
  "modified": "2026-07-20T15:31:45Z",
  "published": "2026-07-19T12:30:22Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-53395"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/8371cc5c0a2cc2a71b3dcfd47ff1f7fcfc526a5e"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/a60f25a800846ab8e5a13f8a9d05111f2aee55a7"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2026-53395 (GCVE-0-2026-53395)

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

Title

nfsd: fix dead ACL conflict guard in nfsd4_create

Summary

In the Linux kernel, the following vulnerability has been resolved: nfsd: fix dead ACL conflict guard in nfsd4_create nfsd4_create() steals create->cr_dpacl/cr_pacl into the local nfsd_attrs via the designated initializer, then immediately sets the source pointers to NULL. The subsequent conflict guard tests the already-nilled source fields, making it permanently dead code: if (create->cr_acl) { if (create->cr_dpacl || create->cr_pacl) /* always false */ When a client encodes both FATTR4_WORD0_ACL and FATTR4_WORD2_POSIX_{DEFAULT,ACCESS}_ACL in the same CREATE fattr bitmap, nfsd4_acl_to_attr() overwrites attrs.na_pacl/na_dpacl without releasing the originals, leaking two posix_acl slab objects per request. Repeated requests cause unbounded slab exhaustion. Fix by checking attrs.na_dpacl/na_pacl (the stolen values) instead of the nilled create->cr_dpacl/cr_pacl, matching the correct pattern already used in nfsd4_setattr().

Severity

7.5 (High)


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

Assigner

Linux mitre root

References

2 references

URL	Tags
https://git.kernel.org/stable/c/8371cc5c0a2cc2a71…
https://git.kernel.org/stable/c/a60f25a800846ab8e…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: d2ca50606f5f0235d7780c1cd73b6614a5d07620 , < 8371cc5c0a2cc2a71b3dcfd47ff1f7fcfc526a5e (git) Affected: d2ca50606f5f0235d7780c1cd73b6614a5d07620 , < a60f25a800846ab8e5a13f8a9d05111f2aee55a7 (git)
Linux	Linux	Affected: 7.0 Unaffected: 0 , < 7.0 (semver) Unaffected: 7.1.3 , ≤ 7.1.* (semver) Unaffected: 7.2 , ≤ * (original_commit_for_fix)

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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": "8371cc5c0a2cc2a71b3dcfd47ff1f7fcfc526a5e",
              "status": "affected",
              "version": "d2ca50606f5f0235d7780c1cd73b6614a5d07620",
              "versionType": "git"
            },
            {
              "lessThan": "a60f25a800846ab8e5a13f8a9d05111f2aee55a7",
              "status": "affected",
              "version": "d2ca50606f5f0235d7780c1cd73b6614a5d07620",
              "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": "7.0"
            },
            {
              "lessThan": "7.0",
              "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": "7.0",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2",
                  "versionStartIncluding": "7.0",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: fix dead ACL conflict guard in nfsd4_create\n\nnfsd4_create() steals create-\u003ecr_dpacl/cr_pacl into the local\nnfsd_attrs via the designated initializer, then immediately sets the\nsource pointers to NULL. The subsequent conflict guard tests the\nalready-nilled source fields, making it permanently dead code:\n\n    if (create-\u003ecr_acl) {\n        if (create-\u003ecr_dpacl || create-\u003ecr_pacl)  /* always false */\n\nWhen a client encodes both FATTR4_WORD0_ACL and\nFATTR4_WORD2_POSIX_{DEFAULT,ACCESS}_ACL in the same CREATE fattr\nbitmap, nfsd4_acl_to_attr() overwrites attrs.na_pacl/na_dpacl without\nreleasing the originals, leaking two posix_acl slab objects per\nrequest. Repeated requests cause unbounded slab exhaustion.\n\nFix by checking attrs.na_dpacl/na_pacl (the stolen values) instead of\nthe nilled create-\u003ecr_dpacl/cr_pacl, matching the correct pattern\nalready used in nfsd4_setattr()."
        }
      ],
      "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 vulnerability is reached through the in-kernel NFS server (nfsd) processing remotely submitted NFSv4 COMPOUND requests containing OP_CREATE over the network (TCP/2049).\nAC:L - An attacker can reliably trigger the leak by sending CREATE operations with both FATTR4_WORD0_ACL and FATTR4_WORD2_POSIX_DEFAULT/ACCESS_ACL set in the fattr bitmap; no race or uncontrollable conditions are required.\nPR:N - Exploitation requires only network reachability to nfsd and standard NFSv4 client authentication to an export; no elevated Linux privileges on the server are needed beyond being an authorized NFS client.\nUI:N - The leak is triggered entirely by crafted NFS protocol requests with no action required from a human user on the server.\nS:U - Impact is confined to kernel memory exhaustion on the NFS server; it does not cross a security boundary such as a VM or sandbox escape.\nC:N - The bug causes reference leaks of posix_acl slab objects only; there is no out-of-bounds access, use-after-free, or other memory corruption that could disclose data.\nI:N - No data modification or memory corruption occurs; the only effect is unreleased kernel heap allocations.\nA:H - Each malicious CREATE leaks two posix_acl slab objects, and repeated requests cause unbounded slab exhaustion that can render the NFS server and potentially the entire host unavailable through OOM conditions."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-17T04:50:47.054Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/8371cc5c0a2cc2a71b3dcfd47ff1f7fcfc526a5e"
        },
        {
          "url": "https://git.kernel.org/stable/c/a60f25a800846ab8e5a13f8a9d05111f2aee55a7"
        }
      ],
      "title": "nfsd: fix dead ACL conflict guard in nfsd4_create",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-53395",
    "datePublished": "2026-07-19T12:01:57.816Z",
    "dateReserved": "2026-06-09T07:44:35.402Z",
    "dateUpdated": "2026-08-17T04:50:47.054Z",
    "state": "PUBLISHED"
  },
  "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.

Detection rules are retrieved from Rulezet.

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.
Browse all ATT&CK techniques and the vulnerabilities related to each.

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