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FKIE_CVE-2025-39894

Vulnerability from fkie_nvd - Published: 2025-10-01 08:15 - Updated: 2026-07-30 06:23
Summary
In the Linux kernel, the following vulnerability has been resolved: netfilter: br_netfilter: do not check confirmed bit in br_nf_local_in() after confirm When send a broadcast packet to a tap device, which was added to a bridge, br_nf_local_in() is called to confirm the conntrack. If another conntrack with the same hash value is added to the hash table, which can be triggered by a normal packet to a non-bridge device, the below warning may happen. ------------[ cut here ]------------ WARNING: CPU: 1 PID: 96 at net/bridge/br_netfilter_hooks.c:632 br_nf_local_in+0x168/0x200 CPU: 1 UID: 0 PID: 96 Comm: tap_send Not tainted 6.17.0-rc2-dirty #44 PREEMPT(voluntary) RIP: 0010:br_nf_local_in+0x168/0x200 Call Trace: <TASK> nf_hook_slow+0x3e/0xf0 br_pass_frame_up+0x103/0x180 br_handle_frame_finish+0x2de/0x5b0 br_nf_hook_thresh+0xc0/0x120 br_nf_pre_routing_finish+0x168/0x3a0 br_nf_pre_routing+0x237/0x5e0 br_handle_frame+0x1ec/0x3c0 __netif_receive_skb_core+0x225/0x1210 __netif_receive_skb_one_core+0x37/0xa0 netif_receive_skb+0x36/0x160 tun_get_user+0xa54/0x10c0 tun_chr_write_iter+0x65/0xb0 vfs_write+0x305/0x410 ksys_write+0x60/0xd0 do_syscall_64+0xa4/0x260 entry_SYSCALL_64_after_hwframe+0x77/0x7f </TASK> ---[ end trace 0000000000000000 ]--- To solve the hash conflict, nf_ct_resolve_clash() try to merge the conntracks, and update skb->_nfct. However, br_nf_local_in() still use the old ct from local variable 'nfct' after confirm(), which leads to this warning. If confirm() does not insert the conntrack entry and return NF_DROP, the warning may also occur. There is no need to reserve the WARN_ON_ONCE, just remove it.

{
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          "product": "Linux",
          "programFiles": [
            "net/bridge/br_netfilter_hooks.c"
          ],
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          "vendor": "Linux",
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              "versionType": "git"
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              "status": "affected",
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              "versionType": "git"
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              "versionType": "git"
            },
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              "status": "affected",
              "version": "5.15.151",
              "versionType": "semver"
            },
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              "status": "affected",
              "version": "6.1.81",
              "versionType": "semver"
            },
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              "status": "affected",
              "version": "6.6.21",
              "versionType": "semver"
            },
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              "lessThan": "6.8",
              "status": "affected",
              "version": "6.7.9",
              "versionType": "semver"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/bridge/br_netfilter_hooks.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.8"
            },
            {
              "lessThan": "6.8",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.192",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.151",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.105",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.46",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.16.*",
              "status": "unaffected",
              "version": "6.16.6",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "6.17",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "configurations": [
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  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: br_netfilter: do not check confirmed bit in br_nf_local_in() after confirm\n\nWhen send a broadcast packet to a tap device, which was added to a bridge,\nbr_nf_local_in() is called to confirm the conntrack. If another conntrack\nwith the same hash value is added to the hash table, which can be\ntriggered by a normal packet to a non-bridge device, the below warning\nmay happen.\n\n  ------------[ cut here ]------------\n  WARNING: CPU: 1 PID: 96 at net/bridge/br_netfilter_hooks.c:632 br_nf_local_in+0x168/0x200\n  CPU: 1 UID: 0 PID: 96 Comm: tap_send Not tainted 6.17.0-rc2-dirty #44 PREEMPT(voluntary)\n  RIP: 0010:br_nf_local_in+0x168/0x200\n  Call Trace:\n   \u003cTASK\u003e\n   nf_hook_slow+0x3e/0xf0\n   br_pass_frame_up+0x103/0x180\n   br_handle_frame_finish+0x2de/0x5b0\n   br_nf_hook_thresh+0xc0/0x120\n   br_nf_pre_routing_finish+0x168/0x3a0\n   br_nf_pre_routing+0x237/0x5e0\n   br_handle_frame+0x1ec/0x3c0\n   __netif_receive_skb_core+0x225/0x1210\n   __netif_receive_skb_one_core+0x37/0xa0\n   netif_receive_skb+0x36/0x160\n   tun_get_user+0xa54/0x10c0\n   tun_chr_write_iter+0x65/0xb0\n   vfs_write+0x305/0x410\n   ksys_write+0x60/0xd0\n   do_syscall_64+0xa4/0x260\n   entry_SYSCALL_64_after_hwframe+0x77/0x7f\n   \u003c/TASK\u003e\n  ---[ end trace 0000000000000000 ]---\n\nTo solve the hash conflict, nf_ct_resolve_clash() try to merge the\nconntracks, and update skb-\u003e_nfct. However, br_nf_local_in() still use the\nold ct from local variable \u0027nfct\u0027 after confirm(), which leads to this\nwarning.\n\nIf confirm() does not insert the conntrack entry and return NF_DROP, the\nwarning may also occur. There is no need to reserve the WARN_ON_ONCE, just\nremove it."
    }
  ],
  "id": "CVE-2025-39894",
  "lastModified": "2026-07-30T06:23:54.247",
  "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"
      },
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "LOCAL",
          "availabilityImpact": "HIGH",
          "baseScore": 5.5,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 1.8,
        "impactScore": 3.6,
        "source": "nvd@nist.gov",
        "type": "Primary"
      }
    ]
  },
  "published": "2025-10-01T08:15:31.987",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/479a54ab92087318514c82428a87af2d7af1a576"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/50db11e2bbb635e38e3dd096215580d6adb41fb0"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/a74abcf0f09f59daeecf7a3ba9c1d690808b0afe"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/c47ca77fee9071aa543bae592dd2a384f895c8b6"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/ccbad4803225eafe0175d3cb19f0d8d73b504a94"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/d00c8b0daf56012f69075e3377da67878c775e4c"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "tags": [
        "Third Party Advisory"
      ],
      "url": "https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "NVD-CWE-noinfo"
        }
      ],
      "source": "nvd@nist.gov",
      "type": "Primary"
    }
  ]
}



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