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netfilter: nf_tables: fix use-after-free in nf_tables_addchain()

Type: advisorySources: OSV

In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_tables: fix use-after-free in nf_tables_addchain() nf_tables_addchain() publishes the chain to table->chains via list_add_tail_rcu() (in nft_chain_add()) before registering hooks. If nf_tables_register_hook() then fails, the error path calls nft_chain_del() (list_del_rcu()) followed by nf_tables_chain_destroy() with no RCU grace period in between. This creates two use-after-free conditions: 1) Control-plane: nf_tables_dump_chains() traverses table->chains under rcu_read_lock(). A concurrent dump can still be walking the chain when the error path frees it. 2) Packet path: for NFPROTO_INET, nf_register_net_hook() briefly installs the IPv4 hook before IPv6 registration fails. Packets entering nft_do_chain() via the transient IPv4 hook can still be dereferencing chain->blob_gen_X when the error path frees the chain. Add synchronize_rcu() between nft_chain_del() and the chain destroy so that all RCU readers -- both dump threads and in-flight packet evaluation -- have finished before the chain is freed.

Products
Kernel
Affected versions
Not specified
Fixed versions
6.1.165, 6.12.75, 6.18.14, 6.19.4, 6.6.128
CVEs
CVE-2026-23231
Confirmed fixed CVEs
Not specified
Updated in this feed
5 Nov 2026, 04:13 UTC · Revision 1

Source evidence

netfilter: nf_tables: fix use-after-free in nf_tables_addchain()

core-osv · Original source

Published 4 Mar 2026, 12:58 UTC

In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_tables: fix use-after-free in nf_tables_addchain() nf_tables_addchain() publishes the chain to table->chains via list_add_tail_rcu() (in nft_chain_add()) before registering hooks. If nf_tables_register_hook() then fails, the error path calls nft_chain_del() (list_del_rcu()) followed by nf_tables_chain_destroy() with no RCU grace period in between. This creates two use-after-free conditions: 1) Control-plane: nf_tables_dump_chains() traverses table->chains under rcu_read_lock(). A concurrent dump can still be walking the chain when the error path frees it. 2) Packet path: for NFPROTO_INET, nf_register_net_hook() briefly installs the IPv4 hook before IPv6 registration fails. Packets entering nft_do_chain() via the transient IPv4 hook can still be dereferencing chain->blob_gen_X when the error path frees the chain. Add synchronize_rcu() between nft_chain_del() and the chain destroy so that all RCU readers -- both dump threads and in-flight packet evaluation -- have finished before the chain is freed.

osv:CVE-2026-23231

Kernel

Fixed versions: 6.1.165, 6.6.128, 6.12.75, 6.18.14, 6.19.4

Complete source record
{
  "id": "8d5fa2030db19a45df7da678fd27190003957d7e665c008050862ba63a4a76d5",
  "url": "https://osv.dev/vulnerability/CVE-2026-23231",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "netfilter: nf_tables: fix use-after-free in nf_tables_addchain()",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_tables: fix use-after-free in nf_tables_addchain() nf_tables_addchain() publishes the chain to table->chains via list_add_tail_rcu() (in nft_chain_add()) before registering hooks. If nf_tables_register_hook() then fails, the error path calls nft_chain_del() (list_del_rcu()) followed by nf_tables_chain_destroy() with no RCU grace period in between. This creates two use-after-free conditions: 1) Control-plane: nf_tables_dump_chains() traverses table->chains under rcu_read_lock(). A concurrent dump can still be walking the chain when the error path frees it. 2) Packet path: for NFPROTO_INET, nf_register_net_hook() briefly installs the IPv4 hook before IPv6 registration fails. Packets entering nft_do_chain() via the transient IPv4 hook can still be dereferencing chain->blob_gen_X when the error path frees the chain. Add synchronize_rcu() between nft_chain_del() and the chain destroy so that all RCU readers -- both dump threads and in-flight packet evaluation -- have finished before the chain is freed.",
    "evidence": "osv:CVE-2026-23231",
    "products": [
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            "evidence": "/affected/1/ranges"
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        "affected_versions": []
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    "severity": "high",
    "structured": {
      "id": "CVE-2026-23231",
      "aliases": [
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      "metrics": [
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          "type": "CVSS_V3",
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      ],
      "modified": "2026-10-28T02:30:42.435721785Z",
      "provider": "osv",
      "references": [
        "https://cert-portal.siemens.com/productcert/html/ssa-019113.html",
        "https://cert-portal.siemens.com/productcert/html/ssa-082556.html",
        "https://cert-portal.siemens.com/productcert/html/ssa-253495.html",
        "https://cert-portal.siemens.com/productcert/html/ssa-457936.html",
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        "https://git.kernel.org/stable/c/2a6586ecfa4ce1413daaafee250d2590e05f1a33",
        "https://git.kernel.org/stable/c/2f9a4ffeb763aec822f8ff3d1e82202d27d46d4b",
        "https://git.kernel.org/stable/c/7017745068a9068904e1e7a1b170a5785647cc81",
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        "https://git.kernel.org/stable/c/dbd0af8083dd201f07c49110b2ee93710abdff28",
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        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/23xxx/CVE-2026-23231.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-23231",
        "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
      ],
      "provider_metadata": {
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        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/23xxx/CVE-2026-23231.json"
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    },
    "related_cves": [
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  "source_id": "core-osv",
  "document_id": 510170,
  "published_at": "2026-03-04T12:58:42.029+00:00"
}