Vulnerability-Lookup

CVE-2026-52942 (GCVE-0-2026-52942)

Vulnerability from cvelistv5 – Published: 2026-06-24 07:14 – Updated: 2026-06-24 07:14

Title

netfilter: nf_log: validate MAC header was set before dumping it

Summary

In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_log: validate MAC header was set before dumping it The fallback path of dump_mac_header() guards the MAC header access only with "skb->mac_header != skb->network_header", without checking skb_mac_header_was_set(). When the MAC header is unset, mac_header is 0xffff, so the test passes and skb_mac_header(skb) returns skb->head + 0xffff, ~64 KiB past the buffer; the loop then reads dev->hard_header_len bytes out of bounds into the kernel log. This is reachable via the netdev logger: nf_log_unknown_packet() calls dump_mac_header() unconditionally, and an skb sent through AF_PACKET with PACKET_QDISC_BYPASS reaches the egress hook with mac_header still unset (__dev_queue_xmit(), which would reset it, is bypassed). Add the skb_mac_header_was_set() check the ARPHRD_ETHER path already uses, and replace the open-coded MAC header length test with skb_mac_header_len(). Only skbs with an unset MAC header are affected; valid ones are dumped as before. BUG: KASAN: slab-out-of-bounds in dump_mac_header (net/netfilter/nf_log_syslog.c:831) Read of size 1 at addr ffff88800ea49d3f by task exploit/148 Call Trace: kasan_report (mm/kasan/report.c:595) dump_mac_header (net/netfilter/nf_log_syslog.c:831) nf_log_netdev_packet (net/netfilter/nf_log_syslog.c:938 net/netfilter/nf_log_syslog.c:963) nf_log_packet (net/netfilter/nf_log.c:260) nft_log_eval (net/netfilter/nft_log.c:60) nft_do_chain (net/netfilter/nf_tables_core.c:285) nft_do_chain_netdev (net/netfilter/nft_chain_filter.c:307) nf_hook_slow (net/netfilter/core.c:619) nf_hook_direct_egress (net/packet/af_packet.c:257) packet_xmit (net/packet/af_packet.c:280) packet_sendmsg (net/packet/af_packet.c:3114) __sys_sendto (net/socket.c:2265)

Severity

No CVSS data available.

Assigner

Linux

References

7 references

URL	Tags
https://git.kernel.org/stable/c/d704ee9c7bc68a161…
https://git.kernel.org/stable/c/befb8968a2abdfa94…
https://git.kernel.org/stable/c/8a81e336da685423f…
https://git.kernel.org/stable/c/c38d41134085193ef…
https://git.kernel.org/stable/c/af1b7699466f6556b…
https://git.kernel.org/stable/c/65ef7397eb9a296e9…
https://git.kernel.org/stable/c/a84b6fedbc9707878…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 7eb9282cd0efac08b8377cbd5037ba297c77e3f7 , < d704ee9c7bc68a161684c51a7ac05b446dcf38d4 (git) Affected: 7eb9282cd0efac08b8377cbd5037ba297c77e3f7 , < befb8968a2abdfa948d5600ea7f7a509a292a590 (git) Affected: 7eb9282cd0efac08b8377cbd5037ba297c77e3f7 , < 8a81e336da685423f5b64aac4d571e63d674c52a (git) Affected: 7eb9282cd0efac08b8377cbd5037ba297c77e3f7 , < c38d41134085193efd5b237cf513ad5b3421a60d (git) Affected: 7eb9282cd0efac08b8377cbd5037ba297c77e3f7 , < af1b7699466f6556b351fa25d3dc870abfb5d310 (git) Affected: 7eb9282cd0efac08b8377cbd5037ba297c77e3f7 , < 65ef7397eb9a296e91839f5fd10be96f23d332e7 (git) Affected: 7eb9282cd0efac08b8377cbd5037ba297c77e3f7 , < a84b6fedbc97078788be78dbdd7517d143ad1a77 (git)
Linux	Linux	Affected: 2.6.36 Unaffected: 0 , < 2.6.36 (semver) Unaffected: 5.15.210 , ≤ 5.15.* (semver) Unaffected: 6.1.176 , ≤ 6.1.* (semver) Unaffected: 6.6.143 , ≤ 6.6.* (semver) Unaffected: 6.12.94 , ≤ 6.12.* (semver) Unaffected: 6.18.36 , ≤ 6.18.* (semver) Unaffected: 7.0.13 , ≤ 7.0.* (semver) Unaffected: 7.1 , ≤ * (original_commit_for_fix)

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/netfilter/nf_log_syslog.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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              "versionType": "git"
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          "vendor": "Linux",
          "versions": [
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              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
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            {
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              "status": "unaffected",
              "version": "5.15.210",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.176",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.143",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.94",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.36",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.0.*",
              "status": "unaffected",
              "version": "7.0.13",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
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                  "versionEndExcluding": "5.15.210",
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                {
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: nf_log: validate MAC header was set before dumping it\n\nThe fallback path of dump_mac_header() guards the MAC header access\nonly with \"skb-\u003emac_header != skb-\u003enetwork_header\", without checking\nskb_mac_header_was_set(). When the MAC header is unset, mac_header is\n0xffff, so the test passes and skb_mac_header(skb) returns\nskb-\u003ehead + 0xffff, ~64 KiB past the buffer; the loop then reads\ndev-\u003ehard_header_len bytes out of bounds into the kernel log.\n\nThis is reachable via the netdev logger: nf_log_unknown_packet() calls\ndump_mac_header() unconditionally, and an skb sent through AF_PACKET\nwith PACKET_QDISC_BYPASS reaches the egress hook with mac_header still\nunset (__dev_queue_xmit(), which would reset it, is bypassed).\n\nAdd the skb_mac_header_was_set() check the ARPHRD_ETHER path already\nuses, and replace the open-coded MAC header length test with\nskb_mac_header_len(). Only skbs with an unset MAC header are affected;\nvalid ones are dumped as before.\n\n BUG: KASAN: slab-out-of-bounds in dump_mac_header (net/netfilter/nf_log_syslog.c:831)\n Read of size 1 at addr ffff88800ea49d3f by task exploit/148\n Call Trace:\n  kasan_report (mm/kasan/report.c:595)\n  dump_mac_header (net/netfilter/nf_log_syslog.c:831)\n  nf_log_netdev_packet (net/netfilter/nf_log_syslog.c:938 net/netfilter/nf_log_syslog.c:963)\n  nf_log_packet (net/netfilter/nf_log.c:260)\n  nft_log_eval (net/netfilter/nft_log.c:60)\n  nft_do_chain (net/netfilter/nf_tables_core.c:285)\n  nft_do_chain_netdev (net/netfilter/nft_chain_filter.c:307)\n  nf_hook_slow (net/netfilter/core.c:619)\n  nf_hook_direct_egress (net/packet/af_packet.c:257)\n  packet_xmit (net/packet/af_packet.c:280)\n  packet_sendmsg (net/packet/af_packet.c:3114)\n  __sys_sendto (net/socket.c:2265)"
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-06-24T07:14:30.610Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/d704ee9c7bc68a161684c51a7ac05b446dcf38d4"
        },
        {
          "url": "https://git.kernel.org/stable/c/befb8968a2abdfa948d5600ea7f7a509a292a590"
        },
        {
          "url": "https://git.kernel.org/stable/c/8a81e336da685423f5b64aac4d571e63d674c52a"
        },
        {
          "url": "https://git.kernel.org/stable/c/c38d41134085193efd5b237cf513ad5b3421a60d"
        },
        {
          "url": "https://git.kernel.org/stable/c/af1b7699466f6556b351fa25d3dc870abfb5d310"
        },
        {
          "url": "https://git.kernel.org/stable/c/65ef7397eb9a296e91839f5fd10be96f23d332e7"
        },
        {
          "url": "https://git.kernel.org/stable/c/a84b6fedbc97078788be78dbdd7517d143ad1a77"
        }
      ],
      "title": "netfilter: nf_log: validate MAC header was set before dumping it",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-52942",
    "datePublished": "2026-06-24T07:14:30.610Z",
    "dateReserved": "2026-06-09T07:44:35.370Z",
    "dateUpdated": "2026-06-24T07:14:30.610Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-52942",
      "date": "2026-06-24",
      "epss": "0.00169",
      "percentile": "0.06454"
    }
  }
}

GHSA-3P98-FQ5J-WX55

Vulnerability from github – Published: 2026-06-24 09:30 – Updated: 2026-06-24 09:30

Details

In the Linux kernel, the following vulnerability has been resolved:

netfilter: nf_log: validate MAC header was set before dumping it

The fallback path of dump_mac_header() guards the MAC header access only with "skb->mac_header != skb->network_header", without checking skb_mac_header_was_set(). When the MAC header is unset, mac_header is 0xffff, so the test passes and skb_mac_header(skb) returns skb->head + 0xffff, ~64 KiB past the buffer; the loop then reads dev->hard_header_len bytes out of bounds into the kernel log.

This is reachable via the netdev logger: nf_log_unknown_packet() calls dump_mac_header() unconditionally, and an skb sent through AF_PACKET with PACKET_QDISC_BYPASS reaches the egress hook with mac_header still unset (__dev_queue_xmit(), which would reset it, is bypassed).

Add the skb_mac_header_was_set() check the ARPHRD_ETHER path already uses, and replace the open-coded MAC header length test with skb_mac_header_len(). Only skbs with an unset MAC header are affected; valid ones are dumped as before.

BUG: KASAN: slab-out-of-bounds in dump_mac_header (net/netfilter/nf_log_syslog.c:831) Read of size 1 at addr ffff88800ea49d3f by task exploit/148 Call Trace: kasan_report (mm/kasan/report.c:595) dump_mac_header (net/netfilter/nf_log_syslog.c:831) nf_log_netdev_packet (net/netfilter/nf_log_syslog.c:938 net/netfilter/nf_log_syslog.c:963) nf_log_packet (net/netfilter/nf_log.c:260) nft_log_eval (net/netfilter/nft_log.c:60) nft_do_chain (net/netfilter/nf_tables_core.c:285) nft_do_chain_netdev (net/netfilter/nft_chain_filter.c:307) nf_hook_slow (net/netfilter/core.c:619) nf_hook_direct_egress (net/packet/af_packet.c:257) packet_xmit (net/packet/af_packet.c:280) packet_sendmsg (net/packet/af_packet.c:3114) __sys_sendto (net/socket.c:2265)

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JSON

To clipboard

{
  "affected": [],
  "aliases": [
    "CVE-2026-52942"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-06-24T08:16:24Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: nf_log: validate MAC header was set before dumping it\n\nThe fallback path of dump_mac_header() guards the MAC header access\nonly with \"skb-\u003emac_header != skb-\u003enetwork_header\", without checking\nskb_mac_header_was_set(). When the MAC header is unset, mac_header is\n0xffff, so the test passes and skb_mac_header(skb) returns\nskb-\u003ehead + 0xffff, ~64 KiB past the buffer; the loop then reads\ndev-\u003ehard_header_len bytes out of bounds into the kernel log.\n\nThis is reachable via the netdev logger: nf_log_unknown_packet() calls\ndump_mac_header() unconditionally, and an skb sent through AF_PACKET\nwith PACKET_QDISC_BYPASS reaches the egress hook with mac_header still\nunset (__dev_queue_xmit(), which would reset it, is bypassed).\n\nAdd the skb_mac_header_was_set() check the ARPHRD_ETHER path already\nuses, and replace the open-coded MAC header length test with\nskb_mac_header_len(). Only skbs with an unset MAC header are affected;\nvalid ones are dumped as before.\n\n BUG: KASAN: slab-out-of-bounds in dump_mac_header (net/netfilter/nf_log_syslog.c:831)\n Read of size 1 at addr ffff88800ea49d3f by task exploit/148\n Call Trace:\n  kasan_report (mm/kasan/report.c:595)\n  dump_mac_header (net/netfilter/nf_log_syslog.c:831)\n  nf_log_netdev_packet (net/netfilter/nf_log_syslog.c:938 net/netfilter/nf_log_syslog.c:963)\n  nf_log_packet (net/netfilter/nf_log.c:260)\n  nft_log_eval (net/netfilter/nft_log.c:60)\n  nft_do_chain (net/netfilter/nf_tables_core.c:285)\n  nft_do_chain_netdev (net/netfilter/nft_chain_filter.c:307)\n  nf_hook_slow (net/netfilter/core.c:619)\n  nf_hook_direct_egress (net/packet/af_packet.c:257)\n  packet_xmit (net/packet/af_packet.c:280)\n  packet_sendmsg (net/packet/af_packet.c:3114)\n  __sys_sendto (net/socket.c:2265)",
  "id": "GHSA-3p98-fq5j-wx55",
  "modified": "2026-06-24T09:30:49Z",
  "published": "2026-06-24T09:30:49Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-52942"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/65ef7397eb9a296e91839f5fd10be96f23d332e7"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/8a81e336da685423f5b64aac4d571e63d674c52a"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/a84b6fedbc97078788be78dbdd7517d143ad1a77"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/af1b7699466f6556b351fa25d3dc870abfb5d310"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/befb8968a2abdfa948d5600ea7f7a509a292a590"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/c38d41134085193efd5b237cf513ad5b3421a60d"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/d704ee9c7bc68a161684c51a7ac05b446dcf38d4"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}

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.

Detection rules are retrieved from Rulezet.

Action not permitted

CVE-2026-52942 (GCVE-0-2026-52942)

GHSA-3P98-FQ5J-WX55

Tags

Sightings

Nomenclature