CVE-2026-23111 (GCVE-0-2026-23111)

Vulnerability from cvelistv5 – Published: 2026-02-13 13:29 – Updated: 2026-02-13 13:29
VLAI?
Title
netfilter: nf_tables: fix inverted genmask check in nft_map_catchall_activate()
Summary
In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_tables: fix inverted genmask check in nft_map_catchall_activate() nft_map_catchall_activate() has an inverted element activity check compared to its non-catchall counterpart nft_mapelem_activate() and compared to what is logically required. nft_map_catchall_activate() is called from the abort path to re-activate catchall map elements that were deactivated during a failed transaction. It should skip elements that are already active (they don't need re-activation) and process elements that are inactive (they need to be restored). Instead, the current code does the opposite: it skips inactive elements and processes active ones. Compare the non-catchall activate callback, which is correct: nft_mapelem_activate(): if (nft_set_elem_active(ext, iter->genmask)) return 0; /* skip active, process inactive */ With the buggy catchall version: nft_map_catchall_activate(): if (!nft_set_elem_active(ext, genmask)) continue; /* skip inactive, process active */ The consequence is that when a DELSET operation is aborted, nft_setelem_data_activate() is never called for the catchall element. For NFT_GOTO verdict elements, this means nft_data_hold() is never called to restore the chain->use reference count. Each abort cycle permanently decrements chain->use. Once chain->use reaches zero, DELCHAIN succeeds and frees the chain while catchall verdict elements still reference it, resulting in a use-after-free. This is exploitable for local privilege escalation from an unprivileged user via user namespaces + nftables on distributions that enable CONFIG_USER_NS and CONFIG_NF_TABLES. Fix by removing the negation so the check matches nft_mapelem_activate(): skip active elements, process inactive ones.
Severity ?
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 25aa2ad37c2162be1c0bc4fe6397f7e4c13f00f8 , < 8c760ba4e36c750379d13569f23f5a6e185333f5 (git)
Affected: d60be2da67d172aecf866302c91ea11533eca4d9 , < b9b6573421de51829f7ec1cce76d85f5f6fbbd7f (git)
Affected: 628bd3e49cba1c066228e23d71a852c23e26da73 , < 42c574c1504aa089a0a142e4c13859327570473d (git)
Affected: 628bd3e49cba1c066228e23d71a852c23e26da73 , < 1444ff890b4653add12f734ffeffc173d42862dd (git)
Affected: 628bd3e49cba1c066228e23d71a852c23e26da73 , < 8b68a45f9722f2babe9e7bad00aa74638addf081 (git)
Affected: 628bd3e49cba1c066228e23d71a852c23e26da73 , < f41c5d151078c5348271ffaf8e7410d96f2d82f8 (git)
Affected: bc9f791d2593f17e39f87c6e2b3a36549a3705b1 (git)
Affected: 3c7ec098e3b588434a8b07ea9b5b36f04cef1f50 (git)
Affected: a136b7942ad2a50de708f76ea299ccb45ac7a7f9 (git)
Affected: dc7cdf8cbcbf8b13de1df93f356ec04cdeef5c41 (git)
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    Linux Linux Affected: 6.4
Unaffected: 0 , < 6.4 (semver)
Unaffected: 5.15.200 , ≤ 5.15.* (semver)
Unaffected: 6.1.163 , ≤ 6.1.* (semver)
Unaffected: 6.6.124 , ≤ 6.6.* (semver)
Unaffected: 6.12.70 , ≤ 6.12.* (semver)
Unaffected: 6.18.10 , ≤ 6.18.* (semver)
Unaffected: 6.19 , ≤ * (original_commit_for_fix)
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{
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          "product": "Linux",
          "programFiles": [
            "net/netfilter/nf_tables_api.c"
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      "descriptions": [
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          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: nf_tables: fix inverted genmask check in nft_map_catchall_activate()\n\nnft_map_catchall_activate() has an inverted element activity check\ncompared to its non-catchall counterpart nft_mapelem_activate() and\ncompared to what is logically required.\n\nnft_map_catchall_activate() is called from the abort path to re-activate\ncatchall map elements that were deactivated during a failed transaction.\nIt should skip elements that are already active (they don\u0027t need\nre-activation) and process elements that are inactive (they need to be\nrestored). Instead, the current code does the opposite: it skips inactive\nelements and processes active ones.\n\nCompare the non-catchall activate callback, which is correct:\n\n  nft_mapelem_activate():\n    if (nft_set_elem_active(ext, iter-\u003egenmask))\n        return 0;   /* skip active, process inactive */\n\nWith the buggy catchall version:\n\n  nft_map_catchall_activate():\n    if (!nft_set_elem_active(ext, genmask))\n        continue;   /* skip inactive, process active */\n\nThe consequence is that when a DELSET operation is aborted,\nnft_setelem_data_activate() is never called for the catchall element.\nFor NFT_GOTO verdict elements, this means nft_data_hold() is never\ncalled to restore the chain-\u003euse reference count. Each abort cycle\npermanently decrements chain-\u003euse. Once chain-\u003euse reaches zero,\nDELCHAIN succeeds and frees the chain while catchall verdict elements\nstill reference it, resulting in a use-after-free.\n\nThis is exploitable for local privilege escalation from an unprivileged\nuser via user namespaces + nftables on distributions that enable\nCONFIG_USER_NS and CONFIG_NF_TABLES.\n\nFix by removing the negation so the check matches nft_mapelem_activate():\nskip active elements, process inactive ones."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-02-13T13:29:55.895Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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          "url": "https://git.kernel.org/stable/c/b9b6573421de51829f7ec1cce76d85f5f6fbbd7f"
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          "url": "https://git.kernel.org/stable/c/1444ff890b4653add12f734ffeffc173d42862dd"
        },
        {
          "url": "https://git.kernel.org/stable/c/8b68a45f9722f2babe9e7bad00aa74638addf081"
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        {
          "url": "https://git.kernel.org/stable/c/f41c5d151078c5348271ffaf8e7410d96f2d82f8"
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      ],
      "title": "netfilter: nf_tables: fix inverted genmask check in nft_map_catchall_activate()",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-23111",
    "datePublished": "2026-02-13T13:29:55.895Z",
    "dateReserved": "2026-01-13T15:37:45.968Z",
    "dateUpdated": "2026-02-13T13:29:55.895Z",
    "state": "PUBLISHED"
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  "vulnerability-lookup:meta": {
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-23111\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2026-02-13T14:16:10.283\",\"lastModified\":\"2026-02-13T14:23:48.007\",\"vulnStatus\":\"Awaiting Analysis\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nnetfilter: nf_tables: fix inverted genmask check in nft_map_catchall_activate()\\n\\nnft_map_catchall_activate() has an inverted element activity check\\ncompared to its non-catchall counterpart nft_mapelem_activate() and\\ncompared to what is logically required.\\n\\nnft_map_catchall_activate() is called from the abort path to re-activate\\ncatchall map elements that were deactivated during a failed transaction.\\nIt should skip elements that are already active (they don\u0027t need\\nre-activation) and process elements that are inactive (they need to be\\nrestored). Instead, the current code does the opposite: it skips inactive\\nelements and processes active ones.\\n\\nCompare the non-catchall activate callback, which is correct:\\n\\n  nft_mapelem_activate():\\n    if (nft_set_elem_active(ext, iter-\u003egenmask))\\n        return 0;   /* skip active, process inactive */\\n\\nWith the buggy catchall version:\\n\\n  nft_map_catchall_activate():\\n    if (!nft_set_elem_active(ext, genmask))\\n        continue;   /* skip inactive, process active */\\n\\nThe consequence is that when a DELSET operation is aborted,\\nnft_setelem_data_activate() is never called for the catchall element.\\nFor NFT_GOTO verdict elements, this means nft_data_hold() is never\\ncalled to restore the chain-\u003euse reference count. Each abort cycle\\npermanently decrements chain-\u003euse. Once chain-\u003euse reaches zero,\\nDELCHAIN succeeds and frees the chain while catchall verdict elements\\nstill reference it, resulting in a use-after-free.\\n\\nThis is exploitable for local privilege escalation from an unprivileged\\nuser via user namespaces + nftables on distributions that enable\\nCONFIG_USER_NS and CONFIG_NF_TABLES.\\n\\nFix by removing the negation so the check matches nft_mapelem_activate():\\nskip active elements, process inactive ones.\"}],\"metrics\":{},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/1444ff890b4653add12f734ffeffc173d42862dd\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/42c574c1504aa089a0a142e4c13859327570473d\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/8b68a45f9722f2babe9e7bad00aa74638addf081\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/8c760ba4e36c750379d13569f23f5a6e185333f5\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/b9b6573421de51829f7ec1cce76d85f5f6fbbd7f\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/f41c5d151078c5348271ffaf8e7410d96f2d82f8\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}"
  }
}


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  • 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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