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flow_dissector: check device type before reading ETH_ADDRS

Type: advisorySource: Official CVE List1 source record

In the Linux kernel, the following vulnerability has been resolved: flow_dissector: check device type before reading ETH_ADDRS __skb_flow_dissect() unconditionally reads 12 bytes from eth_hdr(skb) when FLOW_DISSECTOR_KEY_ETH_ADDRS is requested. This assumes the skb has a valid Ethernet header at mac_header, which is not always the case. The problem can be triggered by: 1. Creating a TUN device in L3 mode (IFF_TUN, hard_header_len=0) 2. Attaching a multiq qdisc with a flower filter matching on eth_src 3. Sending a packet through AF_PACKET Since TUN in L3 mode has no link-layer header, mac_header points to the L3 data area. The flow dissector reads 12 bytes of uninitialized skb memory, which then propagates through fl_set_masked_key() and is used as a rhashtable lookup key in __fl_lookup(), as reported by KMSAN. Rejecting the filter in the control path (at tc filter add time) is not feasible because TC filter blocks can be shared between arbitrary devices -- a filter installed on an Ethernet device may later classify packets on a headerless device through a shared block. The device association is not fixed at filter creation time. Fix this by gating the memcpy on dev->type == ARPHRD_ETHER, which ensures only true Ethernet-framed packets have their addresses read. This is more precise than the previous hard_header_len >= 12 check, which would incorrectly pass for non-Ethernet link types like IPoIB (ARPHRD_INFINIBAND, hard_header_len=24) and FDDI (hard_header_len=21) whose L2 hea

Announced Source revision 1
Original source ↗

CVE-2026-72444

Primary source · Revision 1

Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.

Security context

Source reference: cve:CVE-2026-72444

Linux

Source reference: /containers/cna/affected/0/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Linux

Source reference: /containers/cna/affected/1/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Structured affected-version data

Original package identities and version rules from this source.

[
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "67a900cc0436d74e7ff89042371760def087680d",
        "lessThan": "0fe6455b8e1a22414f39c07bc90a1df12b52ec74",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "67a900cc0436d74e7ff89042371760def087680d",
        "lessThan": "9a65860959db594dfc1820c7fdc09285fb7556bf",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "67a900cc0436d74e7ff89042371760def087680d",
        "lessThan": "594c90b197141944f25991b8314de5c26ee27a7e",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "67a900cc0436d74e7ff89042371760def087680d",
        "lessThan": "c6d3bcb0f934d4297ac5fa1c8656ae40694fb601",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "67a900cc0436d74e7ff89042371760def087680d",
        "lessThan": "825de39f0c35a112148799b3cbe45af3766c018a",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "67a900cc0436d74e7ff89042371760def087680d",
        "lessThan": "bf6e8af2c8be77489bedeae9f8a9654cb710e500",
        "versionType": "git"
      }
    ],
    "programFiles": [
      "net/core/flow_dissector.c"
    ],
    "defaultStatus": "unaffected"
  },
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "4.2"
      },
      {
        "status": "unaffected",
        "version": "0",
        "lessThan": "4.2",
        "versionType": "semver"
      },
      {
        "status": "unaffected",
        "version": "6.1.178",
        "versionType": "semver",
        "lessThanOrEqual": "6.1.*"
      },
      {
        "status": "unaffected",
        "version": "6.6.145",
        "versionType": "semver",
        "lessThanOrEqual": "6.6.*"
      },
      {
        "status": "unaffected",
        "version": "6.12.97",
        "versionType": "semver",
        "lessThanOrEqual": "6.12.*"
      },
      {
        "status": "unaffected",
        "version": "6.18.40",
        "versionType": "semver",
        "lessThanOrEqual": "6.18.*"
      },
      {
        "status": "unaffected",
        "version": "7.1.5",
        "versionType": "semver",
        "lessThanOrEqual": "7.1.*"
      },
      {
        "status": "unaffected",
        "version": "7.2",
        "versionType": "original_commit_for_fix",
        "lessThanOrEqual": "*"
      }
    ],
    "programFiles": [
      "net/core/flow_dissector.c"
    ],
    "defaultStatus": "affected"
  }
]
Related CVEs
CVE-2026-72444

Source reference: /cveMetadata/cveId

Publisher severity

high

Source reference: /containers/cna/metrics

Event
#33054 · Revision 1
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Publisher date
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