GCVE Workshop - 22 September 2026 (14:00-18:00), Luxembourg Before The Vulnopticon Conference - Registration

CVE-2026-72408 (GCVE-0-2026-72408)

Vulnerability from cvelistv5 – Published: 2026-08-15 05:56 – Updated: 2026-08-17 05:43
VLAI
Title
geneve: gate GRO hint in geneve_gro_complete() on gs->gro_hint
Summary
In the Linux kernel, the following vulnerability has been resolved: geneve: gate GRO hint in geneve_gro_complete() on gs->gro_hint geneve_gro_receive() reads the GRO hint through geneve_sk_gro_hint_off(), which honours it only when the socket enabled IFLA_GENEVE_GRO_HINT (gs->gro_hint). geneve_gro_complete() instead calls the low-level geneve_opt_gro_hint_off() and acts on the hint unconditionally. On a tunnel without the hint, receive aggregates the frames as plain ETH_P_TEB while complete still honours an attacker-supplied hint option: it inflates gh_len by gro_hint->nested_hdr_len (u8) and redirects the dispatch type, so the inner gro_complete handler runs at nhoff + gh_len, an offset receive never pulled nor validated, reading out of bounds of the skb head: BUG: KASAN: slab-out-of-bounds in ipv6_gro_complete (net/ipv6/ip6_offload.c:196) Read of size 1 at addr ffff88800fe91980 by task exploit/153 ipv6_gro_complete (net/ipv6/ip6_offload.c:196) geneve_gro_complete (drivers/net/geneve.c:965) udp_gro_complete (net/ipv4/udp_offload.c:940) inet_gro_complete (net/ipv4/af_inet.c:1621) __gro_flush (net/core/gro.c:306) Gate the complete path on gs->gro_hint too via geneve_sk_gro_hint_off(), so both paths agree. Tunnels that enable the hint are unaffected.
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 , < 49c2e7c0a69999a75ef5eaebe1559a20d0b3c15a (git)
Affected: fd0dd796576e1a560e1441e665810129f0a82be0 , < 2651c174445884ac9e85622aeade9c1f7b98d8e5 (git)
guessed Create a notification for this product.
Linux Linux Affected: 7.0
Unaffected: 0 , < 7.0 (semver)
Unaffected: 7.1.5 , ≤ 7.1.* (semver)
Unaffected: 7.2 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
Show details on NVD website
To clipboard 

{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/net/geneve.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "49c2e7c0a69999a75ef5eaebe1559a20d0b3c15a",
              "status": "affected",
              "version": "fd0dd796576e1a560e1441e665810129f0a82be0",
              "versionType": "git"
            },
            {
              "lessThan": "2651c174445884ac9e85622aeade9c1f7b98d8e5",
              "status": "affected",
              "version": "fd0dd796576e1a560e1441e665810129f0a82be0",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "drivers/net/geneve.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "7.0"
            },
            {
              "lessThan": "7.0",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.5",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.1.5",
                  "versionStartIncluding": "7.0",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2",
                  "versionStartIncluding": "7.0",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ngeneve: gate GRO hint in geneve_gro_complete() on gs-\u003egro_hint\n\ngeneve_gro_receive() reads the GRO hint through geneve_sk_gro_hint_off(),\nwhich honours it only when the socket enabled IFLA_GENEVE_GRO_HINT\n(gs-\u003egro_hint). geneve_gro_complete() instead calls the low-level\ngeneve_opt_gro_hint_off() and acts on the hint unconditionally.\n\nOn a tunnel without the hint, receive aggregates the frames as plain\nETH_P_TEB while complete still honours an attacker-supplied hint option: it\ninflates gh_len by gro_hint-\u003enested_hdr_len (u8) and redirects the dispatch\ntype, so the inner gro_complete handler runs at nhoff + gh_len, an offset\nreceive never pulled nor validated, reading out of bounds of the skb head:\n\n  BUG: KASAN: slab-out-of-bounds in ipv6_gro_complete (net/ipv6/ip6_offload.c:196)\n  Read of size 1 at addr ffff88800fe91980 by task exploit/153\n   ipv6_gro_complete (net/ipv6/ip6_offload.c:196)\n   geneve_gro_complete (drivers/net/geneve.c:965)\n   udp_gro_complete (net/ipv4/udp_offload.c:940)\n   inet_gro_complete (net/ipv4/af_inet.c:1621)\n   __gro_flush (net/core/gro.c:306)\n\nGate the complete path on gs-\u003egro_hint too via geneve_sk_gro_hint_off(), so\nboth paths agree. Tunnels that enable the hint are unaffected."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 10,
            "baseSeverity": "CRITICAL",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - The bug is triggered by remotely delivered UDP/GENEVE packets processed in the NAPI GRO completion path (udp_gro_complete \u2192 geneve_gro_complete \u2192 __gro_flush), not via local syscalls or physical interfaces.\nAC:L - The attacker controls all packet fields (GRO hint option, nested_hdr_len, inner_proto_id) and can send multiple matching datagrams to force GRO aggregation/flush; no uncontrollable race or memory layout is required.\nPR:N - No authentication or local privileges are needed; any remote host that can send UDP to a victim\u0027s GENEVE tunnel port triggers the flaw on default tunnels without IFLA_GENEVE_GRO_HINT enabled.\nUI:N - Exploitation requires only transmission of crafted network packets; no victim interaction such as opening files, mounting filesystems, or clicking links is needed.\nS:C - In cloud/Kubernetes overlay deployments using GENEVE, a malicious tenant VM or pod can attack the host/hypervisor kernel over the underlay network, crossing the tenant-to-host security boundary.\nC:H - geneve_gro_complete() honors attacker-supplied GRO hint options that gro_receive() ignored, inflating gh_len and dispatching inner gro_complete past validated skb data, causing slab out-of-bounds reads and enabling arbitrary kernel memory disclosure.\nI:H - Misdirected gro_complete handlers (e.g., ipv6_gro_complete) read and rewrite protocol header fields at attacker-chosen offsets beyond the skb head, providing out-of-bounds write primitives exploitable for control-flow hijacking.\nA:H - The vulnerability provokes KASAN slab-out-of-bounds faults and kernel oops during GRO flush; repeated remote triggering can panic or hang the host, denying availability to all workloads."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-17T05:43:48.541Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/49c2e7c0a69999a75ef5eaebe1559a20d0b3c15a"
        },
        {
          "url": "https://git.kernel.org/stable/c/2651c174445884ac9e85622aeade9c1f7b98d8e5"
        }
      ],
      "title": "geneve: gate GRO hint in geneve_gro_complete() on gs-\u003egro_hint",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-72408",
    "datePublished": "2026-08-15T05:56:31.477Z",
    "dateReserved": "2026-08-09T03:40:39.926Z",
    "dateUpdated": "2026-08-17T05:43:48.541Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-72408",
      "date": "2026-09-04",
      "epss": "0.0038",
      "percentile": "0.31061"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-72408\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2026-08-15T06:22:14.397\",\"lastModified\":\"2026-08-17T06:19:07.570\",\"vulnStatus\":\"Received\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\ngeneve: gate GRO hint in geneve_gro_complete() on gs-\u003egro_hint\\n\\ngeneve_gro_receive() reads the GRO hint through geneve_sk_gro_hint_off(),\\nwhich honours it only when the socket enabled IFLA_GENEVE_GRO_HINT\\n(gs-\u003egro_hint). geneve_gro_complete() instead calls the low-level\\ngeneve_opt_gro_hint_off() and acts on the hint unconditionally.\\n\\nOn a tunnel without the hint, receive aggregates the frames as plain\\nETH_P_TEB while complete still honours an attacker-supplied hint option: it\\ninflates gh_len by gro_hint-\u003enested_hdr_len (u8) and redirects the dispatch\\ntype, so the inner gro_complete handler runs at nhoff + gh_len, an offset\\nreceive never pulled nor validated, reading out of bounds of the skb head:\\n\\n  BUG: KASAN: slab-out-of-bounds in ipv6_gro_complete (net/ipv6/ip6_offload.c:196)\\n  Read of size 1 at addr ffff88800fe91980 by task exploit/153\\n   ipv6_gro_complete (net/ipv6/ip6_offload.c:196)\\n   geneve_gro_complete (drivers/net/geneve.c:965)\\n   udp_gro_complete (net/ipv4/udp_offload.c:940)\\n   inet_gro_complete (net/ipv4/af_inet.c:1621)\\n   __gro_flush (net/core/gro.c:306)\\n\\nGate the complete path on gs-\u003egro_hint too via geneve_sk_gro_hint_off(), so\\nboth paths agree. Tunnels that enable the hint are unaffected.\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"drivers/net/geneve.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"fd0dd796576e1a560e1441e665810129f0a82be0\",\"lessThan\":\"49c2e7c0a69999a75ef5eaebe1559a20d0b3c15a\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"fd0dd796576e1a560e1441e665810129f0a82be0\",\"lessThan\":\"2651c174445884ac9e85622aeade9c1f7b98d8e5\",\"versionType\":\"git\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"drivers/net/geneve.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"7.0\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"7.0\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.1.5\",\"lessThanOrEqual\":\"7.1.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.2\",\"lessThanOrEqual\":\"*\",\"versionType\":\"original_commit_for_fix\",\"status\":\"unaffected\"}]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H\",\"baseScore\":10.0,\"baseSeverity\":\"CRITICAL\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"scope\":\"CHANGED\",\"confidentialityImpact\":\"HIGH\",\"integrityImpact\":\"HIGH\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":3.9,\"impactScore\":6.0}]},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/2651c174445884ac9e85622aeade9c1f7b98d8e5\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/49c2e7c0a69999a75ef5eaebe1559a20d0b3c15a\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}",
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-08-19T17:41:51+00:00",
      "cve": "CVE-2026-72408",
      "id": "CVE-2026-72408",
      "initial_release_date": "2026-08-15T00:00:00+00:00",
      "product_status:known_affected": "76",
      "product_status:known_not_affected": "198",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: geneve: gate GRO hint in geneve_gro_complete() on gs-\u003egro_hint",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-72408.json",
      "version": "3"
    }
  }
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.





Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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.