Vulnerability-Lookup

GHSA-95VH-JXQC-H2W9

Vulnerability from github – Published: 2026-10-18 18:32 – Updated: 2026-10-18 18:32

Details

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.

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{
  "affected": [],
  "aliases": [
    "CVE-2026-98851"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-10-18T16:17:39Z",
    "severity": null
  },
  "details": "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.",
  "id": "GHSA-95vh-jxqc-h2w9",
  "modified": "2026-10-18T18:32:06Z",
  "published": "2026-10-18T18:32:06Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-98851"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/4cd378423a33194a773c267fc58606d28fce95cf"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/64ac0cb574c740bf723affb79b646eeba920db6b"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/747928b5d4ff8c8de55138a54c13980e4bb88578"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/c5f91098edee98c015f78488460a0609e62582a5"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}

CVE-2026-98851 (GCVE-0-2026-98851)

Vulnerability from cvelistv5 – Published: 2026-10-18 15:50 – Updated: 2026-10-19 09:26

Title

netfilter: nft_flow_offload: drop flowtable reference on init error path

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.

Severity

No CVSS data available.

Assigner

Linux CNA under the mitre root

CNA scorecard D 53/100 over 6996 records in the last 180 days details

References

4 references

URL	Tags
https://git.kernel.org/stable/c/64ac0cb574c740bf7…
https://git.kernel.org/stable/c/c5f91098edee98c01…
https://git.kernel.org/stable/c/4cd378423a33194a7…
https://git.kernel.org/stable/c/747928b5d4ff8c8de…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: a3c90f7a2323b331ae816d5b0633e68148e25d04 , < 64ac0cb574c740bf723affb79b646eeba920db6b (git) Affected: a3c90f7a2323b331ae816d5b0633e68148e25d04 , < c5f91098edee98c015f78488460a0609e62582a5 (git) Affected: a3c90f7a2323b331ae816d5b0633e68148e25d04 , < 4cd378423a33194a773c267fc58606d28fce95cf (git) Affected: a3c90f7a2323b331ae816d5b0633e68148e25d04 , < 747928b5d4ff8c8de55138a54c13980e4bb88578 (git)
Linux	Linux	Affected: 4.16 Unaffected: 0 , < 4.16 (semver) Unaffected: 6.12.113 , ≤ 6.12.* (semver) Unaffected: 6.18.56 , ≤ 6.18.* (semver) Unaffected: 7.2.10 , ≤ 7.2.* (semver) Unaffected: 7.3 , ≤ * (original_commit_for_fix)

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        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/netfilter/nft_flow_offload.c"
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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.

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