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

Vulnerability from cvelistv5 – Published: 2026-09-11 19:46 – Updated: 2026-09-11 19:46
VLAI
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
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: f5b3108e6a14418b120a3c38ca589b8d6cf87627 , < f3adf1643517357221422c05986d6de5df7b9913 (git)
Affected: f5b3108e6a14418b120a3c38ca589b8d6cf87627 , < 0fd2b9687dae36be5b84eab39b4c627bb7ab33b3 (git)
Affected: f5b3108e6a14418b120a3c38ca589b8d6cf87627 , < 2092f5b38f88be306140c77aeeeb43fc1adacacc (git)
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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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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/nfs/nfs4client.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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              "status": "affected",
              "version": "f5b3108e6a14418b120a3c38ca589b8d6cf87627",
              "versionType": "git"
            },
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          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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              "status": "affected",
              "version": "6.17"
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              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
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              "versionType": "semver"
            },
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              "version": "7.2.4",
              "versionType": "semver"
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              "status": "unaffected",
              "version": "7.3-rc1",
              "versionType": "original_commit_for_fix"
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      "cpeApplicability": [
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          "nodes": [
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              "cpeMatch": [
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                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.50",
                  "versionStartIncluding": "6.17",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.4",
                  "versionStartIncluding": "6.17",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3-rc1",
                  "versionStartIncluding": "6.17",
                  "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",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/f3adf1643517357221422c05986d6de5df7b9913"
        },
        {
          "url": "https://git.kernel.org/stable/c/0fd2b9687dae36be5b84eab39b4c627bb7ab33b3"
        },
        {
          "url": "https://git.kernel.org/stable/c/2092f5b38f88be306140c77aeeeb43fc1adacacc"
        }
      ],
      "title": "NFS: fix delegation_hash_table leak when nfs4_server_common_setup() fails",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-89714",
    "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",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-89714",
      "date": "2026-09-15",
      "epss": "0.00198",
      "percentile": "0.09746"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-89714\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2026-09-11T20:19:58.873\",\"lastModified\":\"2026-09-11T20:19:58.873\",\"vulnStatus\":\"Received\",\"cveTags\":[],\"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.\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"fs/nfs/nfs4client.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"f5b3108e6a14418b120a3c38ca589b8d6cf87627\",\"lessThan\":\"f3adf1643517357221422c05986d6de5df7b9913\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"f5b3108e6a14418b120a3c38ca589b8d6cf87627\",\"lessThan\":\"0fd2b9687dae36be5b84eab39b4c627bb7ab33b3\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"f5b3108e6a14418b120a3c38ca589b8d6cf87627\",\"lessThan\":\"2092f5b38f88be306140c77aeeeb43fc1adacacc\",\"versionType\":\"git\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"fs/nfs/nfs4client.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"6.17\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"6.17\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.18.50\",\"lessThanOrEqual\":\"6.18.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.2.4\",\"lessThanOrEqual\":\"7.2.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.3-rc1\",\"lessThanOrEqual\":\"*\",\"versionType\":\"original_commit_for_fix\",\"status\":\"unaffected\"}]}]}],\"metrics\":{},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/0fd2b9687dae36be5b84eab39b4c627bb7ab33b3\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/2092f5b38f88be306140c77aeeeb43fc1adacacc\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/f3adf1643517357221422c05986d6de5df7b9913\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}",
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-09-15T05:03:19+00:00",
      "cve": "CVE-2026-89714",
      "id": "CVE-2026-89714",
      "initial_release_date": "2026-09-11T19:46:28.476000+00:00",
      "product_status:known_affected": "2",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: Linux kernel NFS: Denial of Service due to unbounded memory leak from failed mount attempts",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89714.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "not set",
      "current_release_date": "2026-09-12T16:23:04Z",
      "cve": "CVE-2026-89714",
      "id": "CVE-2026-89714",
      "initial_release_date": "2026-09-12T16:23:04Z",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-89714",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-89714.json",
      "version": "2"
    }
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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  • 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.
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  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


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