CVE-2026-72407 (GCVE-0-2026-72407)

Vulnerability from cvelistv5 – Published: 2026-08-15 05:56 – Updated: 2026-08-17 05:43
VLAI
Title
geneve: validate inner network offset in geneve_gro_complete()
Summary
In the Linux kernel, the following vulnerability has been resolved: geneve: validate inner network offset in geneve_gro_complete() Even with both paths gated on gs->gro_hint, geneve_gro_complete() re-derives the inner dispatch type and length from the packet and the current gs->gro_hint, independently of geneve_gro_receive(). The two can disagree if gs->gro_hint flips under a concurrent geneve_quiesce()/ geneve_unquiesce() (sk_user_data is NULL across a synchronize_net()), or if the re-read option bytes differ from the ones receive parsed. geneve_gro_receive() already records the inner network header position in NAPI_GRO_CB()->inner_network_offset. Have geneve_gro_complete() compute the offset it is about to dispatch at, adding ETH_HLEN in the ETH_P_TEB case where eth_gro_complete() steps over the inner MAC header, and bail out if it lands past inner_network_offset. Use a lower bound rather than exact equality: between gh_len and the inner L3 header, geneve_gro_receive() may also have pulled an inner VLAN tag (vlan_gro_receive() advances the recorded offset past it), which only moves inner_network_offset further out. A valid frame therefore always satisfies inner_nh <= inner_network_offset, while a gh_len inflated by a hint gro_receive() did not honour dispatches past the validated inner header, i.e. the out-of-bounds completion. Only the latter is rejected.
Severity
10 (Critical)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: fd0dd796576e1a560e1441e665810129f0a82be0 , < e2087447f562692ff0cd08a0554d8d4ad083aa5c (git)
Affected: fd0dd796576e1a560e1441e665810129f0a82be0 , < cbb0d30a1ad6fc9439b1dc9b4f5a7a9140d3b11f (git)
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Linux Linux Affected: 7.0
Unaffected: 0 , < 7.0 (semver)
Unaffected: 7.1.5 , ≤ 7.1.* (semver)
Unaffected: 7.2 , ≤ * (original_commit_for_fix)
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{
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          "product": "Linux",
          "programFiles": [
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ngeneve: validate inner network offset in geneve_gro_complete()\n\nEven with both paths gated on gs-\u003egro_hint, geneve_gro_complete()\nre-derives the inner dispatch type and length from the packet and the\ncurrent gs-\u003egro_hint, independently of geneve_gro_receive(). The two can\ndisagree if gs-\u003egro_hint flips under a concurrent geneve_quiesce()/\ngeneve_unquiesce() (sk_user_data is NULL across a synchronize_net()), or if\nthe re-read option bytes differ from the ones receive parsed.\n\ngeneve_gro_receive() already records the inner network header position in\nNAPI_GRO_CB()-\u003einner_network_offset. Have geneve_gro_complete() compute the\noffset it is about to dispatch at, adding ETH_HLEN in the ETH_P_TEB case\nwhere eth_gro_complete() steps over the inner MAC header, and bail out if\nit lands past inner_network_offset.\n\nUse a lower bound rather than exact equality: between gh_len and the inner\nL3 header, geneve_gro_receive() may also have pulled an inner VLAN tag\n(vlan_gro_receive() advances the recorded offset past it), which only moves\ninner_network_offset further out. A valid frame therefore always satisfies\ninner_nh \u003c= inner_network_offset, while a gh_len inflated by a hint\ngro_receive() did not honour dispatches past the validated inner header,\ni.e. the out-of-bounds completion. Only the latter is rejected."
        }
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            "baseSeverity": "CRITICAL",
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          "scenarios": [
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              "lang": "en",
              "value": "AV:N - The bug is in geneve_gro_complete() on the NAPI GRO receive path for UDP-encapsulated GENEVE frames; a remote peer can deliver crafted packets to a listening GENEVE UDP port on cloud/overlay hosts without local access.\nAC:L - An attacker can reliably trigger the mismatch by flooding GRO-eligible GENEVE frames with crafted GRO-hint options and timing them against geneve_quiesce()/geneve_unquiesce() during changelink, or self-trigger that race with CAP_NET_ADMIN in a user namespace.\nPR:N - Exploitation requires no credentials or capabilities on the victim; the attacker only needs network reachability to a host already running a gro_hint-enabled GENEVE tunnel, which is common on overlay networks.\nUI:N - Exploitation is fully automated through malicious network traffic and does not require any victim user action such as mounting filesystems or opening files.\nS:C - On cloud/overlay deployments a tenant VM or remote overlay peer can corrupt the hypervisor/host kernel through underlay GENEVE GRO processing, crossing the guest/host security boundary.\nC:H - When gro_complete() dispatches past inner_network_offset, eth_gro_complete() and inet_gro_complete() read headers from attacker-influenced out-of-bounds skb memory, enabling arbitrary kernel memory disclosure.\nI:H - The same out-of-bounds gro_complete dispatch writes header fields (e.g., iph-\u003etot_len and iph-\u003echeck in inet_gro_complete()), causing memory corruption that can be leveraged for arbitrary write or code execution.\nA:H - Out-of-bounds GRO completion can cause kernel oops/panic or forced skb drop under error paths, enabling repeatable remote denial of service against the host."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-17T05:43:47.398Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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      "title": "geneve: validate inner network offset in geneve_gro_complete()",
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    "cveId": "CVE-2026-72407",
    "datePublished": "2026-08-15T05:56:30.847Z",
    "dateReserved": "2026-08-09T03:40:39.926Z",
    "dateUpdated": "2026-08-17T05:43:47.398Z",
    "state": "PUBLISHED"
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            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ngeneve: validate inner network offset in geneve_gro_complete()\n\nEven with both paths gated on gs-\u003egro_hint, geneve_gro_complete()\nre-derives the inner dispatch type and length from the packet and the\ncurrent gs-\u003egro_hint, independently of geneve_gro_receive(). The two can\ndisagree if gs-\u003egro_hint flips under a concurrent geneve_quiesce()/\ngeneve_unquiesce() (sk_user_data is NULL across a synchronize_net()), or if\nthe re-read option bytes differ from the ones receive parsed.\n\ngeneve_gro_receive() already records the inner network header position in\nNAPI_GRO_CB()-\u003einner_network_offset. Have geneve_gro_complete() compute the\noffset it is about to dispatch at, adding ETH_HLEN in the ETH_P_TEB case\nwhere eth_gro_complete() steps over the inner MAC header, and bail out if\nit lands past inner_network_offset.\n\nUse a lower bound rather than exact equality: between gh_len and the inner\nL3 header, geneve_gro_receive() may also have pulled an inner VLAN tag\n(vlan_gro_receive() advances the recorded offset past it), which only moves\ninner_network_offset further out. A valid frame therefore always satisfies\ninner_nh \u003c= inner_network_offset, while a gh_len inflated by a hint\ngro_receive() did not honour dispatches past the validated inner header,\ni.e. the out-of-bounds completion. Only the latter is rejected."
          }
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        "id": "CVE-2026-72407",
        "lastModified": "2026-08-17T06:19:07.453",
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      "cve": "CVE-2026-72407",
      "id": "CVE-2026-72407",
      "initial_release_date": "2026-08-15T00:00:00+00:00",
      "product_status:known_affected": "76",
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      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: geneve: validate inner network offset in geneve_gro_complete()",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-72407.json",
      "version": "3"
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      "current_release_date": "2026-09-15T01:26:06Z",
      "cve": "CVE-2026-72407",
      "id": "CVE-2026-72407",
      "initial_release_date": "2026-08-26T01:14:39Z",
      "product_status:known_affected": "123",
      "product_status:known_not_affected": "239",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-72407",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-72407.json",
      "version": "6"
    }
  }
}



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