Vulnerability-Lookup

GHSA-3GWR-8CWH-87H2

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: 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.

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-2026-53394"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-401"
    ],
    "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: 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.",
  "id": "GHSA-3gwr-8cwh-87h2",
  "modified": "2026-07-20T15:31:45Z",
  "published": "2026-07-19T12:30:22Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-53394"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/017a6150106b054cc84d1b0582d97bd3a74d4281"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/57aee7a35bb12753057c5b65d72d1f46c0e95b07"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/a10bf67fe06469a71a401f72f328237345d553c0"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/c9aefb2b5f11337c9202c5bd0c45d71198449718"
    }
  ],
  "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-2026-53394 (GCVE-0-2026-53394)

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

Title

nfsd: avoid leaking pre-allocated openowner on unconfirmed retry race

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.

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

4 references

URL	Tags
https://git.kernel.org/stable/c/c9aefb2b5f11337c9…
https://git.kernel.org/stable/c/017a6150106b054cc…
https://git.kernel.org/stable/c/a10bf67fe06469a71…
https://git.kernel.org/stable/c/57aee7a35bb127530…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 23df17788c6212809848f836b10c4f85b16843a5 , < c9aefb2b5f11337c9202c5bd0c45d71198449718 (git) Affected: 23df17788c6212809848f836b10c4f85b16843a5 , < 017a6150106b054cc84d1b0582d97bd3a74d4281 (git) Affected: 23df17788c6212809848f836b10c4f85b16843a5 , < a10bf67fe06469a71a401f72f328237345d553c0 (git) Affected: 23df17788c6212809848f836b10c4f85b16843a5 , < 57aee7a35bb12753057c5b65d72d1f46c0e95b07 (git)
Linux	Linux	Affected: 6.10 Unaffected: 0 , < 6.10 (semver) Unaffected: 6.12.95 , ≤ 6.12.* (semver) Unaffected: 6.18.38 , ≤ 6.18.* (semver) Unaffected: 7.1.3 , ≤ 7.1.* (semver) Unaffected: 7.2 , ≤ * (original_commit_for_fix)

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      "affected": [
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          "defaultStatus": "unaffected",
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          "programFiles": [
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          "versions": [
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              "status": "affected",
              "version": "6.10"
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                  "versionStartIncluding": "6.10",
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                {
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        }
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              "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."
            }
          ]
        }
      ],
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        "dateUpdated": "2026-08-17T04:50:45.946Z",
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        "shortName": "Linux"
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          "url": "https://git.kernel.org/stable/c/57aee7a35bb12753057c5b65d72d1f46c0e95b07"
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      "title": "nfsd: avoid leaking pre-allocated openowner on unconfirmed retry race",
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    "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"
  },
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  "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.
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