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

Vulnerability from cvelistv5 – Published: 2026-10-18 15:50 – Updated: 2026-10-18 15:50
VLAI
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 7100 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: a3c90f7a2323b331ae816d5b0633e68148e25d04 , < 64ac0cb574c740bf723affb79b646eeba920db6b (git)
Affected: a3c90f7a2323b331ae816d5b0633e68148e25d04 , < c5f91098edee98c015f78488460a0609e62582a5 (git)
Affected: a3c90f7a2323b331ae816d5b0633e68148e25d04 , < 4cd378423a33194a773c267fc58606d28fce95cf (git)
Affected: a3c90f7a2323b331ae816d5b0633e68148e25d04 , < 747928b5d4ff8c8de55138a54c13980e4bb88578 (git)
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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-rc6 , ≤ * (original_commit_for_fix)
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{
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          "product": "Linux",
          "programFiles": [
            "net/netfilter/nft_flow_offload.c"
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          "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."
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        "dateUpdated": "2026-10-18T15:50:50.910Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-98851",
    "datePublished": "2026-10-18T15:50:50.910Z",
    "dateReserved": "2026-09-25T10:25:14.376Z",
    "dateUpdated": "2026-10-18T15:50:50.910Z",
    "state": "PUBLISHED"
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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."
          }
        ],
        "id": "CVE-2026-98851",
        "lastModified": "2026-10-18T16:17:39.490",
        "metrics": {},
        "published": "2026-10-18T16:17:39.490",
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        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Received"
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}



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