Vulnerability-Lookup

FKIE_CVE-2026-72418

Vulnerability from fkie_nvd - Published: 2026-08-15 06:22 - Updated: 2026-10-16 19:17

Severity

7.5 (High) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Summary

In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_conncount: prevent connlimit drops for early confirmed ct Commit 69894e5b4c5e ("netfilter: nft_connlimit: update the count if add was skipped") introduced a regression where packets for valid connections are dropped when using connlimit for soft-limiting scenarios. The issue occurs when a new connection reuses a socket currently in the TIME_WAIT state. In this scenario, the connection tracking entry is evaluated as already confirmed. Previously, __nf_conncount_add() assumed that if a connection was confirmed and did not originate from the loopback interface, it should skip the addition and return -EEXIST. Skipping the addition triggers a garbage collection run that cleans up the TIME_WAIT connection. Consequently, the active connection count drops to 0, which xt_connlimit mishandles, leading to the false rejection of the perfectly valid new connection. Fix this by replacing the interface check with protocol-agnostic state checks. We now skip the tree insertion and preserve the lockless garbage collection optimization only if the connection is IPS_ASSURED. This allows early-confirmed setup packets (such as reused TIME_WAIT sockets or locally generated SYN-ACKs) to be properly evaluated and counted without falsely dropping. The goto check_connections path is maintained to ensure these setup packets are deduplicated correctly. This has been tested with slowhttptest and HTTP server configured locally to ensure we are not breaking soft-limiting scenarios for local or external connections. In addition, it was tested with a OVS zone limit too.

References

	URL	Tags
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/000ac6830b56499d6b65fd91486ce6689eb02be4
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/329f2626ee5cb8fafdf6b58b624311529c57cb45
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/3793d24de224943e0a6016bbeffb6f5c4cea2e3d
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/abef7f817217fcb62c11821d6b895063eadb2828
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/be52572c6d55f677ba76869d3c63805c0d4891a3
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/c8b6f36f766991e3ebebec6596daee4b04dcbc49
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/cbe2d14a7c5b1fc71821fbfee5c4963917411e92
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/ebfe8249ba79e4ff0f1e3aad8787b992ef27f026

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/netfilter/nf_conncount.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "000ac6830b56499d6b65fd91486ce6689eb02be4",
              "status": "affected",
              "version": "460c112e1d887b58b06b56e8e0230058906ff2c3",
              "versionType": "git"
            },
            {
              "lessThan": "cbe2d14a7c5b1fc71821fbfee5c4963917411e92",
              "status": "affected",
              "version": "53bc0ac47f4f7621c991807bc90e01df49561ac8",
              "versionType": "git"
            },
            {
              "lessThan": "3793d24de224943e0a6016bbeffb6f5c4cea2e3d",
              "status": "affected",
              "version": "ca8b4d1d6304a84ce2016fa2fe9a114b9607b839",
              "versionType": "git"
            },
            {
              "lessThan": "abef7f817217fcb62c11821d6b895063eadb2828",
              "status": "affected",
              "version": "8286c02fe9100330475331253fc590f047963f90",
              "versionType": "git"
            },
            {
              "lessThan": "ebfe8249ba79e4ff0f1e3aad8787b992ef27f026",
              "status": "affected",
              "version": "b29ddccf36946a90323486221f39e9f88cc01b8e",
              "versionType": "git"
            },
            {
              "lessThan": "329f2626ee5cb8fafdf6b58b624311529c57cb45",
              "status": "affected",
              "version": "77ea3d8ac3d3d59b5ac9ad639e4ba107c0f2ff1e",
              "versionType": "git"
            },
            {
              "lessThan": "be52572c6d55f677ba76869d3c63805c0d4891a3",
              "status": "affected",
              "version": "69894e5b4c5e28cda5f32af33d4a92b7a4b93b0e",
              "versionType": "git"
            },
            {
              "lessThan": "c8b6f36f766991e3ebebec6596daee4b04dcbc49",
              "status": "affected",
              "version": "69894e5b4c5e28cda5f32af33d4a92b7a4b93b0e",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "f85623af16b83615e5f64a9b19ae1d584805cb07",
              "versionType": "git"
            },
            {
              "lessThan": "5.10.261",
              "status": "affected",
              "version": "5.10.248",
              "versionType": "semver"
            },
            {
              "lessThan": "5.15.212",
              "status": "affected",
              "version": "5.15.198",
              "versionType": "semver"
            },
            {
              "lessThan": "6.1.178",
              "status": "affected",
              "version": "6.1.160",
              "versionType": "semver"
            },
            {
              "lessThan": "6.6.145",
              "status": "affected",
              "version": "6.6.120",
              "versionType": "semver"
            },
            {
              "lessThan": "6.12.97",
              "status": "affected",
              "version": "6.12.63",
              "versionType": "semver"
            },
            {
              "lessThan": "6.18.40",
              "status": "affected",
              "version": "6.18.2",
              "versionType": "semver"
            },
            {
              "lessThan": "6.18",
              "status": "affected",
              "version": "6.17.13",
              "versionType": "semver"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/netfilter/nf_conncount.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.19"
            },
            {
              "lessThan": "6.19",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.10.*",
              "status": "unaffected",
              "version": "5.10.261",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.212",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.178",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.145",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.97",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.40",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.5",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "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."
    }
  ],
  "id": "CVE-2026-72418",
  "lastModified": "2026-10-16T19:17:29.033",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 7.5,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 3.6,
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-72418",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "yes"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-10-16T18:49:23.434729Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-08-15T06:22:15.420",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/000ac6830b56499d6b65fd91486ce6689eb02be4"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/329f2626ee5cb8fafdf6b58b624311529c57cb45"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/3793d24de224943e0a6016bbeffb6f5c4cea2e3d"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/abef7f817217fcb62c11821d6b895063eadb2828"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/be52572c6d55f677ba76869d3c63805c0d4891a3"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/c8b6f36f766991e3ebebec6596daee4b04dcbc49"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/cbe2d14a7c5b1fc71821fbfee5c4963917411e92"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/ebfe8249ba79e4ff0f1e3aad8787b992ef27f026"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}

CVE-2026-72418 (GCVE-0-2026-72418)

Vulnerability from cvelistv5 – Published: 2026-08-15 05:56 – Updated: 2026-10-16 18:55

Title

netfilter: nf_conncount: prevent connlimit drops for early confirmed ct

Summary

Severity

7.5 (High)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

SSVC

Exploitation: none Automatable: yes Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-10-16 18:49 UTC

Assigner

Linux CNA under the mitre root

CNA scorecard D 53/100 over 6992 records in the last 180 days details

References

8 references

URL	Tags
https://git.kernel.org/stable/c/000ac6830b56499d6…
https://git.kernel.org/stable/c/cbe2d14a7c5b1fc71…
https://git.kernel.org/stable/c/3793d24de224943e0…
https://git.kernel.org/stable/c/abef7f817217fcb62…
https://git.kernel.org/stable/c/ebfe8249ba79e4ff0…
https://git.kernel.org/stable/c/329f2626ee5cb8faf…
https://git.kernel.org/stable/c/be52572c6d55f677b…
https://git.kernel.org/stable/c/c8b6f36f766991e3e…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 460c112e1d887b58b06b56e8e0230058906ff2c3 , < 000ac6830b56499d6b65fd91486ce6689eb02be4 (git) Affected: 53bc0ac47f4f7621c991807bc90e01df49561ac8 , < cbe2d14a7c5b1fc71821fbfee5c4963917411e92 (git) Affected: ca8b4d1d6304a84ce2016fa2fe9a114b9607b839 , < 3793d24de224943e0a6016bbeffb6f5c4cea2e3d (git) Affected: 8286c02fe9100330475331253fc590f047963f90 , < abef7f817217fcb62c11821d6b895063eadb2828 (git) Affected: b29ddccf36946a90323486221f39e9f88cc01b8e , < ebfe8249ba79e4ff0f1e3aad8787b992ef27f026 (git) Affected: 77ea3d8ac3d3d59b5ac9ad639e4ba107c0f2ff1e , < 329f2626ee5cb8fafdf6b58b624311529c57cb45 (git) Affected: 69894e5b4c5e28cda5f32af33d4a92b7a4b93b0e , < be52572c6d55f677ba76869d3c63805c0d4891a3 (git) Affected: 69894e5b4c5e28cda5f32af33d4a92b7a4b93b0e , < c8b6f36f766991e3ebebec6596daee4b04dcbc49 (git) Affected: f85623af16b83615e5f64a9b19ae1d584805cb07 (git) Affected: 5.10.248 , < 5.10.261 (semver) Affected: 5.15.198 , < 5.15.212 (semver) Affected: 6.1.160 , < 6.1.178 (semver) Affected: 6.6.120 , < 6.6.145 (semver) Affected: 6.12.63 , < 6.12.97 (semver) Affected: 6.18.2 , < 6.18.40 (semver) Affected: 6.17.13 , < 6.18 (semver)
Linux	Linux	Affected: 6.19 Unaffected: 0 , < 6.19 (semver) Unaffected: 5.10.261 , ≤ 5.10.* (semver) Unaffected: 5.15.212 , ≤ 5.15.* (semver) Unaffected: 6.1.178 , ≤ 6.1.* (semver) Unaffected: 6.6.145 , ≤ 6.6.* (semver) Unaffected: 6.12.97 , ≤ 6.12.* (semver) Unaffected: 6.18.40 , ≤ 6.18.* (semver) Unaffected: 7.1.5 , ≤ 7.1.* (semver) Unaffected: 7.2 , ≤ * (original_commit_for_fix)

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-72418",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-10-16T18:49:23.434729Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-10-16T18:55:22.660Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/netfilter/nf_conncount.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "000ac6830b56499d6b65fd91486ce6689eb02be4",
              "status": "affected",
              "version": "460c112e1d887b58b06b56e8e0230058906ff2c3",
              "versionType": "git"
            },
            {
              "lessThan": "cbe2d14a7c5b1fc71821fbfee5c4963917411e92",
              "status": "affected",
              "version": "53bc0ac47f4f7621c991807bc90e01df49561ac8",
              "versionType": "git"
            },
            {
              "lessThan": "3793d24de224943e0a6016bbeffb6f5c4cea2e3d",
              "status": "affected",
              "version": "ca8b4d1d6304a84ce2016fa2fe9a114b9607b839",
              "versionType": "git"
            },
            {
              "lessThan": "abef7f817217fcb62c11821d6b895063eadb2828",
              "status": "affected",
              "version": "8286c02fe9100330475331253fc590f047963f90",
              "versionType": "git"
            },
            {
              "lessThan": "ebfe8249ba79e4ff0f1e3aad8787b992ef27f026",
              "status": "affected",
              "version": "b29ddccf36946a90323486221f39e9f88cc01b8e",
              "versionType": "git"
            },
            {
              "lessThan": "329f2626ee5cb8fafdf6b58b624311529c57cb45",
              "status": "affected",
              "version": "77ea3d8ac3d3d59b5ac9ad639e4ba107c0f2ff1e",
              "versionType": "git"
            },
            {
              "lessThan": "be52572c6d55f677ba76869d3c63805c0d4891a3",
              "status": "affected",
              "version": "69894e5b4c5e28cda5f32af33d4a92b7a4b93b0e",
              "versionType": "git"
            },
            {
              "lessThan": "c8b6f36f766991e3ebebec6596daee4b04dcbc49",
              "status": "affected",
              "version": "69894e5b4c5e28cda5f32af33d4a92b7a4b93b0e",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "f85623af16b83615e5f64a9b19ae1d584805cb07",
              "versionType": "git"
            },
            {
              "lessThan": "5.10.261",
              "status": "affected",
              "version": "5.10.248",
              "versionType": "semver"
            },
            {
              "lessThan": "5.15.212",
              "status": "affected",
              "version": "5.15.198",
              "versionType": "semver"
            },
            {
              "lessThan": "6.1.178",
              "status": "affected",
              "version": "6.1.160",
              "versionType": "semver"
            },
            {
              "lessThan": "6.6.145",
              "status": "affected",
              "version": "6.6.120",
              "versionType": "semver"
            },
            {
              "lessThan": "6.12.97",
              "status": "affected",
              "version": "6.12.63",
              "versionType": "semver"
            },
            {
              "lessThan": "6.18.40",
              "status": "affected",
              "version": "6.18.2",
              "versionType": "semver"
            },
            {
              "lessThan": "6.18",
              "status": "affected",
              "version": "6.17.13",
              "versionType": "semver"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/netfilter/nf_conncount.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.19"
            },
            {
              "lessThan": "6.19",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.10.*",
              "status": "unaffected",
              "version": "5.10.261",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.212",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.178",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.145",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.97",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.40",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.5",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
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          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.10.261",
                  "versionStartIncluding": "5.10.248",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.15.212",
                  "versionStartIncluding": "5.15.198",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.1.178",
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                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.97",
                  "versionStartIncluding": "6.12.63",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.40",
                  "versionStartIncluding": "6.18.2",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                  "vulnerable": true
                },
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              ],
              "negate": false,
              "operator": "OR"
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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"
          },
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              "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."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-17T05:43:58.352Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
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          "url": "https://git.kernel.org/stable/c/000ac6830b56499d6b65fd91486ce6689eb02be4"
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          "url": "https://git.kernel.org/stable/c/cbe2d14a7c5b1fc71821fbfee5c4963917411e92"
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          "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",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "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"
}

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.

Vulnerability timeline

Sightings and recorded dates, grouped by day · UTC

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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.

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