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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: nf_conncount: prevent connlimit drops for early confirmed ct\n\nCommit 69894e5b4c5e (\"netfilter: nft_connlimit: update the count if add\nwas skipped\") introduced a regression where packets for valid\nconnections are dropped when using connlimit for soft-limiting\nscenarios.\n\nThe issue occurs when a new connection reuses a socket currently in\nthe TIME_WAIT state. In this scenario, the connection tracking entry\nis evaluated as already confirmed. Previously, __nf_conncount_add()\nassumed that if a connection was confirmed and did not originate from\nthe loopback interface, it should skip the addition and return -EEXIST.\n\nSkipping the addition triggers a garbage collection run that cleans up\nthe TIME_WAIT connection. Consequently, the active connection count\ndrops to 0, which xt_connlimit mishandles, leading to the false rejection\nof the perfectly valid new connection.\n\nFix this by replacing the interface check with protocol-agnostic state\nchecks. We now skip the tree insertion and preserve the lockless garbage\ncollection optimization only if the connection is IPS_ASSURED. This\nallows early-confirmed setup packets (such as reused TIME_WAIT sockets\nor locally generated SYN-ACKs) to be properly evaluated and counted\nwithout falsely dropping. The goto check_connections path is maintained\nto ensure these setup packets are deduplicated correctly.\n\nThis has been tested with slowhttptest and HTTP server configured\nlocally to ensure we are not breaking soft-limiting scenarios for local\nor external connections. In addition, it was tested with a OVS zone\nlimit too."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.5,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - Exploitation is triggered by remote TCP packets processed through netfilter INPUT/FORWARD hooks (xt_connlimit, nft_connlimit, OVS ct-limit) that call nf_conncount_count_skb() on received skbs; no local syscall or ioctl is required.\nAC:L - An unauthenticated remote attacker can reliably trigger the bug by rapidly reconnecting to reuse a TIME_WAIT 4-tuple, a normal TCP behavior they fully control; no race against unrelated system events is required.\nPR:N - The attacker needs no privileges on the victim host; only inbound network access to a service protected by admin-configured connlimit rules is required, and no CAP_NET_ADMIN or namespace capabilities are needed to trigger the faulty counting path.\nUI:N - No victim user action is required; exploitation is achieved solely by sending crafted connection patterns over the network to a host already running connlimit enforcement.\nS:U - Impact is confined to incorrect netfilter connection accounting and packet drops within the same kernel/network security domain; there is no cross-boundary escape such as VM breakout or privilege escalation.\nC:N - The flaw is a connection-count bookkeeping error and premature garbage collection; it does not read kernel memory, leak data, or involve any memory corruption primitive.\nI:N - No unauthorized modification of data or code occurs; the only effect is dropping or mis-evaluating packets against connlimit policy, which is an availability concern rather than integrity compromise.\nA:H - When the miscount drives the connection count to zero, xt_connlimit hot-drops valid packets, falsely rejecting legitimate new connections and causing repeatable denial of service against protected services without authentication."
            }
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        }
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        "dateUpdated": "2026-08-17T05:43:58.352Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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      "references": [
        {
          "url": "https://git.kernel.org/stable/c/000ac6830b56499d6b65fd91486ce6689eb02be4"
        },
        {
          "url": "https://git.kernel.org/stable/c/cbe2d14a7c5b1fc71821fbfee5c4963917411e92"
        },
        {
          "url": "https://git.kernel.org/stable/c/3793d24de224943e0a6016bbeffb6f5c4cea2e3d"
        },
        {
          "url": "https://git.kernel.org/stable/c/abef7f817217fcb62c11821d6b895063eadb2828"
        },
        {
          "url": "https://git.kernel.org/stable/c/ebfe8249ba79e4ff0f1e3aad8787b992ef27f026"
        },
        {
          "url": "https://git.kernel.org/stable/c/329f2626ee5cb8fafdf6b58b624311529c57cb45"
        },
        {
          "url": "https://git.kernel.org/stable/c/be52572c6d55f677ba76869d3c63805c0d4891a3"
        },
        {
          "url": "https://git.kernel.org/stable/c/c8b6f36f766991e3ebebec6596daee4b04dcbc49"
        }
      ],
      "title": "netfilter: nf_conncount: prevent connlimit drops for early confirmed ct",
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  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-72418",
    "datePublished": "2026-08-15T05:56:38.374Z",
    "dateReserved": "2026-08-09T03:40:39.927Z",
    "dateUpdated": "2026-10-16T18:55:22.660Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

{
  "affected": [],
  "aliases": [
    "CVE-2026-72418"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-08-15T06:22:15Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: nf_conncount: prevent connlimit drops for early confirmed ct\n\nCommit 69894e5b4c5e (\"netfilter: nft_connlimit: update the count if add\nwas skipped\") introduced a regression where packets for valid\nconnections are dropped when using connlimit for soft-limiting\nscenarios.\n\nThe issue occurs when a new connection reuses a socket currently in\nthe TIME_WAIT state. In this scenario, the connection tracking entry\nis evaluated as already confirmed. Previously, __nf_conncount_add()\nassumed that if a connection was confirmed and did not originate from\nthe loopback interface, it should skip the addition and return -EEXIST.\n\nSkipping the addition triggers a garbage collection run that cleans up\nthe TIME_WAIT connection. Consequently, the active connection count\ndrops to 0, which xt_connlimit mishandles, leading to the false rejection\nof the perfectly valid new connection.\n\nFix this by replacing the interface check with protocol-agnostic state\nchecks. We now skip the tree insertion and preserve the lockless garbage\ncollection optimization only if the connection is IPS_ASSURED. This\nallows early-confirmed setup packets (such as reused TIME_WAIT sockets\nor locally generated SYN-ACKs) to be properly evaluated and counted\nwithout falsely dropping. The goto check_connections path is maintained\nto ensure these setup packets are deduplicated correctly.\n\nThis has been tested with slowhttptest and HTTP server configured\nlocally to ensure we are not breaking soft-limiting scenarios for local\nor external connections. In addition, it was tested with a OVS zone\nlimit too.",
  "id": "GHSA-prxp-6xjx-9qx5",
  "modified": "2026-08-17T06:33:28Z",
  "published": "2026-08-15T06:32:23Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-72418"
    },
    {
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      "url": "https://git.kernel.org/stable/c/abef7f817217fcb62c11821d6b895063eadb2828"
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      "url": "https://git.kernel.org/stable/c/be52572c6d55f677ba76869d3c63805c0d4891a3"
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    {
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  "schema_version": "1.4.0",
  "severity": [
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      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
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}