CVE-2026-98851 (GCVE-0-2026-98851)
Vulnerability from cvelistv5
Published
2026-10-18 15:50
Modified
2026-10-21 12:57
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: netfilter: nft_flow_offload: drop flowtable reference on init error path nft_flow_offload_init() bumps the flowtable use count with nft_use_inc() before calling nf_ct_netns_get(). When the latter fails, the error is returned as-is and the reference is leaked. The upper layers do not balance it either: nf_tables_newexpr() clears expr->ops when the expression init callback fails, so the nft_expr_more() iteration in nft_rule_expr_deactivate() and nf_tables_rule_destroy() stops right before the failed expression and its ->destroy callback, which would drop the reference, never runs. Each failed rule addition therefore leaks one flowtable reference and the flowtable can no longer be removed: NFT_MSG_DELFLOWTABLE keeps reporting -EBUSY even though no rule references it. Save the nf_ct_netns_get() return value and undo the nft_use_inc() when it fails, restoring the inc/dec pairing within nft_flow_offload_init() itself.
References
Impacted products
Vendor Product Version
Linux Linux Version: a3c90f7a2323b331ae816d5b0633e68148e25d04
Version: a3c90f7a2323b331ae816d5b0633e68148e25d04
Version: a3c90f7a2323b331ae816d5b0633e68148e25d04
Version: a3c90f7a2323b331ae816d5b0633e68148e25d04
Version: a3c90f7a2323b331ae816d5b0633e68148e25d04
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{
  "containers": {
    "cna": {
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        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/netfilter/nft_flow_offload.c"
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          ],
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          "vendor": "Linux",
          "versions": [
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              "version": "4.16"
            },
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              "version": "0",
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              "status": "unaffected",
              "version": "6.18.56",
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            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.10",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
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                  "vulnerable": true
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                {
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                },
                {
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              "negate": false,
              "operator": "OR"
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      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: nft_flow_offload: drop flowtable reference on init error path\n\nnft_flow_offload_init() bumps the flowtable use count with\nnft_use_inc() before calling nf_ct_netns_get().  When the latter\nfails, the error is returned as-is and the reference is leaked.\n\nThe upper layers do not balance it either: nf_tables_newexpr()\nclears expr-\u003eops when the expression init callback fails, so the\nnft_expr_more() iteration in nft_rule_expr_deactivate() and\nnf_tables_rule_destroy() stops right before the failed expression\nand its -\u003edestroy callback, which would drop the reference, never\nruns.\n\nEach failed rule addition therefore leaks one flowtable reference\nand the flowtable can no longer be removed: NFT_MSG_DELFLOWTABLE\nkeeps reporting -EBUSY even though no rule references it.\n\nSave the nf_ct_netns_get() return value and undo the nft_use_inc()\nwhen it fails, restoring the inc/dec pairing within\nnft_flow_offload_init() itself."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-21T12:57:30.875Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/1d27214fd9a4d2c0c6d998fc9d4fb61448a3438e"
        },
        {
          "url": "https://git.kernel.org/stable/c/64ac0cb574c740bf723affb79b646eeba920db6b"
        },
        {
          "url": "https://git.kernel.org/stable/c/c5f91098edee98c015f78488460a0609e62582a5"
        },
        {
          "url": "https://git.kernel.org/stable/c/4cd378423a33194a773c267fc58606d28fce95cf"
        },
        {
          "url": "https://git.kernel.org/stable/c/747928b5d4ff8c8de55138a54c13980e4bb88578"
        }
      ],
      "title": "netfilter: nft_flow_offload: drop flowtable reference on init error path",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-98851",
    "datePublished": "2026-10-18T15:50:50.910Z",
    "dateReserved": "2026-09-25T10:25:14.376Z",
    "dateUpdated": "2026-10-21T12:57:30.875Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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