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FKIE_CVE-2026-72247

Vulnerability from fkie_nvd - Published: 2026-08-15 06:21 - Updated: 2026-08-17 06:18
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: fix zone comparison in tuple dedup The "already exists" dedup logic in __nf_conncount_add() decides whether a connection has already been counted and can be skipped instead of incrementing the connlimit count. It compares the conntrack zone of a list entry with the zone of the connection being added using nf_ct_zone_id() and nf_ct_zone_equal(), passing conn->zone.dir or zone->dir as the direction argument. Those helpers take enum ip_conntrack_dir values: IP_CT_DIR_ORIGINAL is 0 and IP_CT_DIR_REPLY is 1. However, zone->dir is a u8 bitmask: NF_CT_ZONE_DIR_ORIG is 1, NF_CT_ZONE_DIR_REPL is 2 and NF_CT_DEFAULT_ZONE_DIR is 3. Passing that bitmask as the enum direction shifts the meaning of every non-zero value. An ORIG-only zone passes 1 and is tested as REPLY, while REPL-only and default zones pass 2 or 3 and test bits beyond the valid direction range. In those cases nf_ct_zone_id() can fall back to NF_CT_DEFAULT_ZONE_ID instead of using the real zone id, so different zones can be treated as equal and dedup collapses to tuple equality alone. nf_conncount stores and compares the original-direction tuple for a connection. If an skb already has an attached conntrack entry, get_ct_or_tuple_from_skb() explicitly copies ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple, regardless of the packet's ctinfo. Therefore the zone comparison in the tuple dedup path must use IP_CT_DIR_ORIGINAL as well; the zone direction bitmask describes where a zone id applies, not which direction this conncount tuple represents. Fix the two dedup comparisons by passing IP_CT_DIR_ORIGINAL directly. Do not special-case NF_CT_DEFAULT_ZONE_DIR and do not compare raw zone ids: using the existing helpers with IP_CT_DIR_ORIGINAL preserves the direction-aware NF_CT_DEFAULT_ZONE_ID fallback. A default bidirectional zone contains the ORIG bit, so it naturally returns the real zone id; reply-only zones continue to fall back for original-direction tuple comparisons.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/35a56e2a46b90e6bd4ca816b80e9cb8d20dfc3ce
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/3cd9a5792cbea81139c24320986dd0db69e9b5d0
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/4f30a89c0ed2418719a1144881c2635b940b543d
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/6ff07ac5405bea4d4ead3559fc123f987576424a
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/78b5d6dbc860776161f9e9206b06ff8a01f531ab
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/7bdc3c0985ecf17b957811fedcc684acdf698acc
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/82fc35e0da9a91db9a034f8311f18f77a599ae3f
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/f62c41b4910e65da396ec9a8c40c1fe7fe82e449
Impacted products
Vendor Product Version
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": "82fc35e0da9a91db9a034f8311f18f77a599ae3f",
              "status": "affected",
              "version": "21ba8847f857028dc83a0f341e16ecc616e34740",
              "versionType": "git"
            },
            {
              "lessThan": "78b5d6dbc860776161f9e9206b06ff8a01f531ab",
              "status": "affected",
              "version": "21ba8847f857028dc83a0f341e16ecc616e34740",
              "versionType": "git"
            },
            {
              "lessThan": "4f30a89c0ed2418719a1144881c2635b940b543d",
              "status": "affected",
              "version": "21ba8847f857028dc83a0f341e16ecc616e34740",
              "versionType": "git"
            },
            {
              "lessThan": "7bdc3c0985ecf17b957811fedcc684acdf698acc",
              "status": "affected",
              "version": "21ba8847f857028dc83a0f341e16ecc616e34740",
              "versionType": "git"
            },
            {
              "lessThan": "35a56e2a46b90e6bd4ca816b80e9cb8d20dfc3ce",
              "status": "affected",
              "version": "21ba8847f857028dc83a0f341e16ecc616e34740",
              "versionType": "git"
            },
            {
              "lessThan": "3cd9a5792cbea81139c24320986dd0db69e9b5d0",
              "status": "affected",
              "version": "21ba8847f857028dc83a0f341e16ecc616e34740",
              "versionType": "git"
            },
            {
              "lessThan": "6ff07ac5405bea4d4ead3559fc123f987576424a",
              "status": "affected",
              "version": "21ba8847f857028dc83a0f341e16ecc616e34740",
              "versionType": "git"
            },
            {
              "lessThan": "f62c41b4910e65da396ec9a8c40c1fe7fe82e449",
              "status": "affected",
              "version": "21ba8847f857028dc83a0f341e16ecc616e34740",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "525e1dffed8711973f77412729621098a95238e5",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "75af3d78168e654a5cd8bbc4c774f97be836165f",
              "versionType": "git"
            },
            {
              "lessThan": "4.15",
              "status": "affected",
              "version": "4.14.92",
              "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": "4.18"
            },
            {
              "lessThan": "4.18",
              "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: fix zone comparison in tuple dedup\n\nThe \"already exists\" dedup logic in __nf_conncount_add() decides\nwhether a connection has already been counted and can be skipped instead\nof incrementing the connlimit count.  It compares the conntrack zone of a\nlist entry with the zone of the connection being added using\nnf_ct_zone_id() and nf_ct_zone_equal(), passing conn-\u003ezone.dir or\nzone-\u003edir as the direction argument.\n\nThose helpers take enum ip_conntrack_dir values: IP_CT_DIR_ORIGINAL is 0\nand IP_CT_DIR_REPLY is 1.  However, zone-\u003edir is a u8 bitmask:\nNF_CT_ZONE_DIR_ORIG is 1, NF_CT_ZONE_DIR_REPL is 2 and\nNF_CT_DEFAULT_ZONE_DIR is 3.  Passing that bitmask as the enum direction\nshifts the meaning of every non-zero value.  An ORIG-only zone passes 1\nand is tested as REPLY, while REPL-only and default zones pass 2 or 3 and\ntest bits beyond the valid direction range.  In those cases\nnf_ct_zone_id() can fall back to NF_CT_DEFAULT_ZONE_ID instead of using\nthe real zone id, so different zones can be treated as equal and dedup\ncollapses to tuple equality alone.\n\nnf_conncount stores and compares the original-direction tuple for a\nconnection.  If an skb already has an attached conntrack entry,\nget_ct_or_tuple_from_skb() explicitly copies\nct-\u003etuplehash[IP_CT_DIR_ORIGINAL].tuple, regardless of the packet\u0027s\nctinfo.  Therefore the zone comparison in the tuple dedup path must use\nIP_CT_DIR_ORIGINAL as well; the zone direction bitmask describes where a\nzone id applies, not which direction this conncount tuple represents.\n\nFix the two dedup comparisons by passing IP_CT_DIR_ORIGINAL directly.\nDo not special-case NF_CT_DEFAULT_ZONE_DIR and do not compare raw zone\nids: using the existing helpers with IP_CT_DIR_ORIGINAL preserves the\ndirection-aware NF_CT_DEFAULT_ZONE_ID fallback.  A default bidirectional\nzone contains the ORIG bit, so it naturally returns the real zone id;\nreply-only zones continue to fall back for original-direction tuple\ncomparisons."
    }
  ],
  "id": "CVE-2026-72247",
  "lastModified": "2026-08-17T06:18:26.563",
  "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"
      }
    ]
  },
  "published": "2026-08-15T06:21:51.887",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/35a56e2a46b90e6bd4ca816b80e9cb8d20dfc3ce"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/3cd9a5792cbea81139c24320986dd0db69e9b5d0"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/4f30a89c0ed2418719a1144881c2635b940b543d"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/6ff07ac5405bea4d4ead3559fc123f987576424a"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/78b5d6dbc860776161f9e9206b06ff8a01f531ab"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/7bdc3c0985ecf17b957811fedcc684acdf698acc"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/82fc35e0da9a91db9a034f8311f18f77a599ae3f"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/f62c41b4910e65da396ec9a8c40c1fe7fe82e449"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}



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