CVE-2026-72417 (GCVE-0-2026-72417)

Vulnerability from cvelistv5 – Published: 2026-08-15 05:56 – Updated: 2026-08-17 05:43
VLAI
Title
netfilter: flowtable: Validate iph->ihl in nf_flow_ip4_tunnel_proto()
Summary
In the Linux kernel, the following vulnerability has been resolved: netfilter: flowtable: Validate iph->ihl in nf_flow_ip4_tunnel_proto() Add sanity check for iph->ihl field in nf_flow_ip4_tunnel_proto() before using it to compute the header size, avoiding out-of-bounds access with malformed IP headers. While at it, use iph->protocol instead of the hardcoded IPPROTO_IPIP constant when setting ctx->tun.proto and reference ctx->tun.hdr_size when updating ctx->offset.
Severity
9.8 (Critical)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: ab427db17885814069bae891834f20842f0ac3a4 , < 025a41e76b51fbc7b8eaa5bacbaa9621d00e6aa7 (git)
Affected: ab427db17885814069bae891834f20842f0ac3a4 , < 84460b644329e25809b4a6d9279d6359d7fd8ebc (git)
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Linux Linux Affected: 6.19
Unaffected: 0 , < 6.19 (semver)
Unaffected: 7.1.5 , ≤ 7.1.* (semver)
Unaffected: 7.2 , ≤ * (original_commit_for_fix)
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/netfilter/nf_flow_table_ip.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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          "product": "Linux",
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          "vendor": "Linux",
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              "version": "6.19"
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              "status": "unaffected",
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              "versionType": "original_commit_for_fix"
            }
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      "cpeApplicability": [
        {
          "nodes": [
            {
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                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                  "versionStartIncluding": "6.19",
                  "vulnerable": true
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                  "vulnerable": true
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              "negate": false,
              "operator": "OR"
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        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: flowtable: Validate iph-\u003eihl in nf_flow_ip4_tunnel_proto()\n\nAdd sanity check for iph-\u003eihl field in nf_flow_ip4_tunnel_proto() before\nusing it to compute the header size, avoiding out-of-bounds access with\nmalformed IP headers.\nWhile at it, use iph-\u003eprotocol instead of the hardcoded IPPROTO_IPIP\nconstant when setting ctx-\u003etun.proto and reference ctx-\u003etun.hdr_size\nwhen updating ctx-\u003eoffset."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 9.8,
            "baseSeverity": "CRITICAL",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - The flaw is hit in nf_flow_offload_ip_hook on NF_NETDEV_INGRESS for IPv4 packets arriving on nftables flowtable devices; a remote attacker can send crafted malformed IP/IPIP headers to that interface without any local access on the victim.\nAC:L - Once a flowtable ingress hook exists, the attacker fully controls packet headers and can reliably reach nf_flow_ip4_tunnel_proto() by sending IP traffic with an invalid ihl field; no race or victim-specific state beyond admin-enabled flow offload is required.\nPR:N - Exploitation requires no credentials or capabilities on the victim host\u2014only that an administrator previously configured nftables flow offload on an ingress device; any remote sender can deliver the malformed packets to trigger parsing on the fast path.\nUI:N - No victim interaction is needed; malicious packets are processed automatically by the netdev ingress netfilter hook during normal receive/forward softirq handling on the configured interface.\nS:U - Impact is kernel memory corruption and crashes within the host kernel security boundary; this is standard in-kernel compromise territory, not a VM escape, IOMMU bypass, or other cross-authority scope change.\nC:H - Missing ihl validation lets iph-\u003eihl\u003c\u003c2 compute an incorrect header size and ctx-\u003eoffset, causing out-of-bounds skb reads in subsequent tuple parsing and forwarding; per kernel guidance, OOB reads warrant High confidentiality impact.\nI:H - Incorrect ctx-\u003eoffset propagates into nf_flow_tuple_ip() and nf_flow_offload_forward(), which invoke skb_ensure_writable() and perform in-place NAT/header mutation at attacker-influenced offsets\u2014memory corruption exploitable for write primitives warrants High integrity impact.\nA:H - Out-of-bounds access in softirq packet processing on the flowtable fast path can trigger KASAN reports, kernel oops, or panics when malformed headers are processed, constituting High availability impact."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-17T05:43:57.257Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/025a41e76b51fbc7b8eaa5bacbaa9621d00e6aa7"
        },
        {
          "url": "https://git.kernel.org/stable/c/84460b644329e25809b4a6d9279d6359d7fd8ebc"
        }
      ],
      "title": "netfilter: flowtable: Validate iph-\u003eihl in nf_flow_ip4_tunnel_proto()",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-72417",
    "datePublished": "2026-08-15T05:56:37.547Z",
    "dateReserved": "2026-08-09T03:40:39.927Z",
    "dateUpdated": "2026-08-17T05:43:57.257Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-72417",
      "date": "2026-09-20",
      "epss": "0.00554",
      "percentile": "0.45071"
    },
    "nvd": {
      "cve": {
        "affected": [
          {
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              {
                "defaultStatus": "unaffected",
                "product": "Linux",
                "programFiles": [
                  "net/netfilter/nf_flow_table_ip.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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                "versions": [
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                    "version": "6.19"
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                    "version": "0",
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                  }
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          }
        ],
        "cveTags": [],
        "descriptions": [
          {
            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: flowtable: Validate iph-\u003eihl in nf_flow_ip4_tunnel_proto()\n\nAdd sanity check for iph-\u003eihl field in nf_flow_ip4_tunnel_proto() before\nusing it to compute the header size, avoiding out-of-bounds access with\nmalformed IP headers.\nWhile at it, use iph-\u003eprotocol instead of the hardcoded IPPROTO_IPIP\nconstant when setting ctx-\u003etun.proto and reference ctx-\u003etun.hdr_size\nwhen updating ctx-\u003eoffset."
          }
        ],
        "id": "CVE-2026-72417",
        "lastModified": "2026-08-17T06:19:08.617",
        "metrics": {
          "cvssMetricV31": [
            {
              "cvssData": {
                "attackComplexity": "LOW",
                "attackVector": "NETWORK",
                "availabilityImpact": "HIGH",
                "baseScore": 9.8,
                "baseSeverity": "CRITICAL",
                "confidentialityImpact": "HIGH",
                "integrityImpact": "HIGH",
                "privilegesRequired": "NONE",
                "scope": "UNCHANGED",
                "userInteraction": "NONE",
                "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
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              "impactScore": 5.9,
              "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
              "type": "Secondary"
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        "published": "2026-08-15T06:22:15.323",
        "references": [
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/025a41e76b51fbc7b8eaa5bacbaa9621d00e6aa7"
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        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Received"
      }
    },
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-08-19T17:40:40+00:00",
      "cve": "CVE-2026-72417",
      "id": "CVE-2026-72417",
      "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: netfilter: flowtable: Validate iph-\u003eihl in nf_flow_ip4_tunnel_proto()",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-72417.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "important",
      "current_release_date": "2026-09-02T11:45:59Z",
      "cve": "CVE-2026-72417",
      "id": "CVE-2026-72417",
      "initial_release_date": "2026-08-27T16:52:49Z",
      "product_status:known_not_affected": "362",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-72417",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-72417.json",
      "version": "3"
    }
  }
}



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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

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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.


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