CVE-2025-39894 (GCVE-0-2025-39894)
Vulnerability from cvelistv5
Published
2025-10-01 07:42
Modified
2025-10-01 07:42
Severity ?
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.
References
Impacted products
Vendor Product Version
Linux Linux Version: 7c3f28599652acf431a2211168de4a583f30b6d5
Version: 2b1414d5e94e477edff1d2c79030f1d742625ea0
Version: 80cd0487f630b5382734997c3e5e3003a77db315
Version: 62e7151ae3eb465e0ab52a20c941ff33bb6332e9
Version: 62e7151ae3eb465e0ab52a20c941ff33bb6332e9
Version: 62e7151ae3eb465e0ab52a20c941ff33bb6332e9
Version: cb734975b0ffa688ff6cc0eed463865bf07b6c01
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/bridge/br_netfilter_hooks.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
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        },
        {
          "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": [
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              "status": "affected",
              "version": "6.8"
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              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
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              "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"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
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                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.15.192",
                  "versionStartIncluding": "5.15.151",
                  "vulnerable": true
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                  "versionEndExcluding": "6.1.151",
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              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "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."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2025-10-01T07:42:43.126Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/d00c8b0daf56012f69075e3377da67878c775e4c"
        },
        {
          "url": "https://git.kernel.org/stable/c/ccbad4803225eafe0175d3cb19f0d8d73b504a94"
        },
        {
          "url": "https://git.kernel.org/stable/c/50db11e2bbb635e38e3dd096215580d6adb41fb0"
        },
        {
          "url": "https://git.kernel.org/stable/c/c47ca77fee9071aa543bae592dd2a384f895c8b6"
        },
        {
          "url": "https://git.kernel.org/stable/c/a74abcf0f09f59daeecf7a3ba9c1d690808b0afe"
        },
        {
          "url": "https://git.kernel.org/stable/c/479a54ab92087318514c82428a87af2d7af1a576"
        }
      ],
      "title": "netfilter: br_netfilter: do not check confirmed bit in br_nf_local_in() after confirm",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2025-39894",
    "datePublished": "2025-10-01T07:42:43.126Z",
    "dateReserved": "2025-04-16T07:20:57.145Z",
    "dateUpdated": "2025-10-01T07:42:43.126Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.1",
  "vulnerability-lookup:meta": {
    "nvd": "{\"cve\":{\"id\":\"CVE-2025-39894\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2025-10-01T08:15:31.987\",\"lastModified\":\"2025-10-02T19:12:17.160\",\"vulnStatus\":\"Awaiting Analysis\",\"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.\"}],\"metrics\":{},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/479a54ab92087318514c82428a87af2d7af1a576\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/50db11e2bbb635e38e3dd096215580d6adb41fb0\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/a74abcf0f09f59daeecf7a3ba9c1d690808b0afe\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/c47ca77fee9071aa543bae592dd2a384f895c8b6\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/ccbad4803225eafe0175d3cb19f0d8d73b504a94\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/d00c8b0daf56012f69075e3377da67878c775e4c\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}"
  }
}


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