Vulnerability-Lookup

GHSA-HV3G-87GW-4M9V

Vulnerability from github – Published: 2026-09-11 21:31 – Updated: 2026-09-11 21:31

Details

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

NFS: fix delegation_hash_table leak when nfs4_server_common_setup() fails

nfs4_server_common_setup() allocates server->delegation_hash_table first, but server->destroy - the only path that frees the table via nfs4_destroy_server() - is not assigned until the very end of the function. If any intermediate step fails (the is_ds_only_client() check, nfs4_init_session(), nfs4_get_rootfh(), or nfs_probe_server()), the function returns with server->destroy still NULL, so the caller's nfs_free_server() skips the destroy callback and the hash table is leaked (4 KiB per attempt with the default delegation watermark).

This is trivially reachable from userspace: every failed NFSv4 mount leaks one allocation. A client that persistently retries a mount that cannot succeed leaks kernel memory without bound. Observed in production where a Longhorn backup poller retried mount.nfs4 against an NFSv3-only server roughly 10 times per second, leaking ~3.4 GiB of unreclaimable slab (kmalloc-rnd-13-4k) per day; the node accumulated 12 GiB of leaked slab before the source was identified via the kmem:kmalloc tracepoint (call_site=nfs4_delegation_hash_alloc).

Reproducer:

# server exports NFSv3 only (or export path absent for v4) while :; do mount -t nfs4 :/missing /mnt; done # watch SUnreclaim in /proc/meminfo grow 4 KiB per iteration

Free the table on the error paths between the allocation and the assignment of server->destroy.

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{
  "affected": [],
  "aliases": [
    "CVE-2026-89714"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-09-11T20:19:58Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nNFS: fix delegation_hash_table leak when nfs4_server_common_setup() fails\n\nnfs4_server_common_setup() allocates server-\u003edelegation_hash_table\nfirst, but server-\u003edestroy - the only path that frees the table via\nnfs4_destroy_server() - is not assigned until the very end of the\nfunction. If any intermediate step fails (the is_ds_only_client()\ncheck, nfs4_init_session(), nfs4_get_rootfh(), or nfs_probe_server()),\nthe function returns with server-\u003edestroy still NULL, so the caller\u0027s\nnfs_free_server() skips the destroy callback and the hash table is\nleaked (4 KiB per attempt with the default delegation watermark).\n\nThis is trivially reachable from userspace: every failed NFSv4 mount\nleaks one allocation. A client that persistently retries a mount that\ncannot succeed leaks kernel memory without bound. Observed in\nproduction where a Longhorn backup poller retried mount.nfs4 against\nan NFSv3-only server roughly 10 times per second, leaking ~3.4 GiB of\nunreclaimable slab (kmalloc-rnd-13-4k) per day; the node accumulated\n12 GiB of leaked slab before the source was identified via the\nkmem:kmalloc tracepoint (call_site=nfs4_delegation_hash_alloc).\n\nReproducer:\n\n  # server exports NFSv3 only (or export path absent for v4)\n  while :; do mount -t nfs4 \u003cserver\u003e:/missing /mnt; done\n  # watch SUnreclaim in /proc/meminfo grow 4 KiB per iteration\n\nFree the table on the error paths between the allocation and the\nassignment of server-\u003edestroy.",
  "id": "GHSA-hv3g-87gw-4m9v",
  "modified": "2026-09-11T21:31:37Z",
  "published": "2026-09-11T21:31:37Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-89714"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/0fd2b9687dae36be5b84eab39b4c627bb7ab33b3"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/2092f5b38f88be306140c77aeeeb43fc1adacacc"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f3adf1643517357221422c05986d6de5df7b9913"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}

CVE-2026-89714 (GCVE-0-2026-89714)

Vulnerability from cvelistv5 – Published: 2026-09-11 19:46 – Updated: 2026-09-11 19:46

Title

NFS: fix delegation_hash_table leak when nfs4_server_common_setup() fails

Summary

In the Linux kernel, the following vulnerability has been resolved: NFS: fix delegation_hash_table leak when nfs4_server_common_setup() fails nfs4_server_common_setup() allocates server->delegation_hash_table first, but server->destroy - the only path that frees the table via nfs4_destroy_server() - is not assigned until the very end of the function. If any intermediate step fails (the is_ds_only_client() check, nfs4_init_session(), nfs4_get_rootfh(), or nfs_probe_server()), the function returns with server->destroy still NULL, so the caller's nfs_free_server() skips the destroy callback and the hash table is leaked (4 KiB per attempt with the default delegation watermark). This is trivially reachable from userspace: every failed NFSv4 mount leaks one allocation. A client that persistently retries a mount that cannot succeed leaks kernel memory without bound. Observed in production where a Longhorn backup poller retried mount.nfs4 against an NFSv3-only server roughly 10 times per second, leaking ~3.4 GiB of unreclaimable slab (kmalloc-rnd-13-4k) per day; the node accumulated 12 GiB of leaked slab before the source was identified via the kmem:kmalloc tracepoint (call_site=nfs4_delegation_hash_alloc). Reproducer: # server exports NFSv3 only (or export path absent for v4) while :; do mount -t nfs4 <server>:/missing /mnt; done # watch SUnreclaim in /proc/meminfo grow 4 KiB per iteration Free the table on the error paths between the allocation and the assignment of server->destroy.

Severity

No CVSS data available.

Assigner

Linux mitre root

References

3 references

URL	Tags
https://git.kernel.org/stable/c/f3adf164351735722…
https://git.kernel.org/stable/c/0fd2b9687dae36be5…
https://git.kernel.org/stable/c/2092f5b38f88be306…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: f5b3108e6a14418b120a3c38ca589b8d6cf87627 , < f3adf1643517357221422c05986d6de5df7b9913 (git) Affected: f5b3108e6a14418b120a3c38ca589b8d6cf87627 , < 0fd2b9687dae36be5b84eab39b4c627bb7ab33b3 (git) Affected: f5b3108e6a14418b120a3c38ca589b8d6cf87627 , < 2092f5b38f88be306140c77aeeeb43fc1adacacc (git)
Linux	Linux	Affected: 6.17 Unaffected: 0 , < 6.17 (semver) Unaffected: 6.18.50 , ≤ 6.18.* (semver) Unaffected: 7.2.4 , ≤ 7.2.* (semver) Unaffected: 7.3-rc1 , ≤ * (original_commit_for_fix)

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JSON

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/nfs/nfs4client.c"
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          "vendor": "Linux",
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              "status": "affected",
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              "versionType": "git"
            },
            {
              "lessThan": "0fd2b9687dae36be5b84eab39b4c627bb7ab33b3",
              "status": "affected",
              "version": "f5b3108e6a14418b120a3c38ca589b8d6cf87627",
              "versionType": "git"
            },
            {
              "lessThan": "2092f5b38f88be306140c77aeeeb43fc1adacacc",
              "status": "affected",
              "version": "f5b3108e6a14418b120a3c38ca589b8d6cf87627",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
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          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.17"
            },
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              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
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            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
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              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.4",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3-rc1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
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          "nodes": [
            {
              "cpeMatch": [
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                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nNFS: fix delegation_hash_table leak when nfs4_server_common_setup() fails\n\nnfs4_server_common_setup() allocates server-\u003edelegation_hash_table\nfirst, but server-\u003edestroy - the only path that frees the table via\nnfs4_destroy_server() - is not assigned until the very end of the\nfunction. If any intermediate step fails (the is_ds_only_client()\ncheck, nfs4_init_session(), nfs4_get_rootfh(), or nfs_probe_server()),\nthe function returns with server-\u003edestroy still NULL, so the caller\u0027s\nnfs_free_server() skips the destroy callback and the hash table is\nleaked (4 KiB per attempt with the default delegation watermark).\n\nThis is trivially reachable from userspace: every failed NFSv4 mount\nleaks one allocation. A client that persistently retries a mount that\ncannot succeed leaks kernel memory without bound. Observed in\nproduction where a Longhorn backup poller retried mount.nfs4 against\nan NFSv3-only server roughly 10 times per second, leaking ~3.4 GiB of\nunreclaimable slab (kmalloc-rnd-13-4k) per day; the node accumulated\n12 GiB of leaked slab before the source was identified via the\nkmem:kmalloc tracepoint (call_site=nfs4_delegation_hash_alloc).\n\nReproducer:\n\n  # server exports NFSv3 only (or export path absent for v4)\n  while :; do mount -t nfs4 \u003cserver\u003e:/missing /mnt; done\n  # watch SUnreclaim in /proc/meminfo grow 4 KiB per iteration\n\nFree the table on the error paths between the allocation and the\nassignment of server-\u003edestroy."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-11T19:46:28.476Z",
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        },
        {
          "url": "https://git.kernel.org/stable/c/2092f5b38f88be306140c77aeeeb43fc1adacacc"
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    "datePublished": "2026-09-11T19:46:28.476Z",
    "dateReserved": "2026-09-11T19:38:34.751Z",
    "dateUpdated": "2026-09-11T19:46:28.476Z",
    "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.
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