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GHSA-MV4H-4H45-G2XR

Vulnerability from github – Published: 2026-08-15 06:32 – Updated: 2026-08-17 06:33

Details

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

netfilter: flowtable: support IPIP tunnel with direct xmit

The combination of IPIP tunnel with direct xmit, eg. bridge device, breaks because no dst_entry is provided to check the skb headroom and to set the iph->frag_off field. This leads to invalid dst usage and can trigger a crash in the tunnel transmit path.

Fix this by moving dst_cache and dst_cookie out of the runtime union so that they can be shared by neighbour, xfrm, and direct tunnel flows. For FLOW_OFFLOAD_XMIT_DIRECT tuples carrying tunnel metadata, preserve route state in these shared fields and release it through the common dst release path.

Since dst_entry is now available to the three supported xmit modes and dst_release() already deals with NULL dst, remove the xmit type check in nft_flow_dst_release(). Moreover, skip the check if the dst entry is NULL in nf_flow_dst_check() which is now the case for the direct xmit case.

Based on patch from Rein Wei n05ec@lzu.edu.cn.

Severity

9.8 (Critical)


                  
                    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

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{
  "affected": [],
  "aliases": [
    "CVE-2026-72248"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-08-15T06:21:52Z",
    "severity": "CRITICAL"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: flowtable: support IPIP tunnel with direct xmit\n\nThe combination of IPIP tunnel with direct xmit, eg. bridge device,\nbreaks because no dst_entry is provided to check the skb headroom and to\nset the iph-\u003efrag_off field. This leads to invalid dst usage and can\ntrigger a crash in the tunnel transmit path.\n\nFix this by moving dst_cache and dst_cookie out of the runtime union so\nthat they can be shared by neighbour, xfrm, and direct tunnel flows.\nFor FLOW_OFFLOAD_XMIT_DIRECT tuples carrying tunnel metadata, preserve\nroute state in these shared fields and release it through the common\ndst release path.\n\nSince dst_entry is now available to the three supported xmit modes and\ndst_release() already deals with NULL dst, remove the xmit type check\nin nft_flow_dst_release(). Moreover, skip the check if the dst entry\nis NULL in nf_flow_dst_check() which is now the case for the direct\nxmit case.\n\nBased on patch from Rein Wei \u003cn05ec@lzu.edu.cn\u003e.",
  "id": "GHSA-mv4h-4h45-g2xr",
  "modified": "2026-08-17T06:33:18Z",
  "published": "2026-08-15T06:32:17Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-72248"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/0880c4ed122d0cddc9f29a2b28f055d1f24f0fca"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/fa7395c02d95e51bad2952325d2d6503bfbad437"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2026-72248 (GCVE-0-2026-72248)

Vulnerability from cvelistv5 – Published: 2026-08-15 05:54 – Updated: 2026-08-17 05:41

Title

netfilter: flowtable: support IPIP tunnel with direct xmit

Summary

In the Linux kernel, the following vulnerability has been resolved: netfilter: flowtable: support IPIP tunnel with direct xmit The combination of IPIP tunnel with direct xmit, eg. bridge device, breaks because no dst_entry is provided to check the skb headroom and to set the iph->frag_off field. This leads to invalid dst usage and can trigger a crash in the tunnel transmit path. Fix this by moving dst_cache and dst_cookie out of the runtime union so that they can be shared by neighbour, xfrm, and direct tunnel flows. For FLOW_OFFLOAD_XMIT_DIRECT tuples carrying tunnel metadata, preserve route state in these shared fields and release it through the common dst release path. Since dst_entry is now available to the three supported xmit modes and dst_release() already deals with NULL dst, remove the xmit type check in nft_flow_dst_release(). Moreover, skip the check if the dst entry is NULL in nf_flow_dst_check() which is now the case for the direct xmit case. Based on patch from Rein Wei <n05ec@lzu.edu.cn>.

Severity

9.8 (Critical)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Assigner

Linux mitre root

References

2 references

URL	Tags
https://git.kernel.org/stable/c/0880c4ed122d0cddc…
https://git.kernel.org/stable/c/fa7395c02d95e51ba…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: d30301ba4b07ac92eb38353a111833b009003170 , < 0880c4ed122d0cddc9f29a2b28f055d1f24f0fca (git) Affected: d30301ba4b07ac92eb38353a111833b009003170 , < fa7395c02d95e51bad2952325d2d6503bfbad437 (git)
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": [
            "include/net/netfilter/nf_flow_table.h",
            "net/netfilter/nf_flow_table_core.c",
            "net/netfilter/nf_flow_table_ip.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "0880c4ed122d0cddc9f29a2b28f055d1f24f0fca",
              "status": "affected",
              "version": "d30301ba4b07ac92eb38353a111833b009003170",
              "versionType": "git"
            },
            {
              "lessThan": "fa7395c02d95e51bad2952325d2d6503bfbad437",
              "status": "affected",
              "version": "d30301ba4b07ac92eb38353a111833b009003170",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "include/net/netfilter/nf_flow_table.h",
            "net/netfilter/nf_flow_table_core.c",
            "net/netfilter/nf_flow_table_ip.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.19"
            },
            {
              "lessThan": "6.19",
              "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": "6.19",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2",
                  "versionStartIncluding": "6.19",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: flowtable: support IPIP tunnel with direct xmit\n\nThe combination of IPIP tunnel with direct xmit, eg. bridge device,\nbreaks because no dst_entry is provided to check the skb headroom and to\nset the iph-\u003efrag_off field. This leads to invalid dst usage and can\ntrigger a crash in the tunnel transmit path.\n\nFix this by moving dst_cache and dst_cookie out of the runtime union so\nthat they can be shared by neighbour, xfrm, and direct tunnel flows.\nFor FLOW_OFFLOAD_XMIT_DIRECT tuples carrying tunnel metadata, preserve\nroute state in these shared fields and release it through the common\ndst release path.\n\nSince dst_entry is now available to the three supported xmit modes and\ndst_release() already deals with NULL dst, remove the xmit type check\nin nft_flow_dst_release(). Moreover, skip the check if the dst entry\nis NULL in nf_flow_dst_check() which is now the case for the direct\nxmit case.\n\nBased on patch from Rein Wei \u003cn05ec@lzu.edu.cn\u003e."
        }
      ],
      "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 bug is hit in the netfilter flowtable ingress fast path when remotely sourced TCP/UDP packets matching an offloaded flow are received on flowtable-bound interfaces, not via netlink configuration APIs.\nAC:L - An attacker can reliably establish the offloaded flow by sending matching traffic and then repeatedly trigger the faulty IPIP direct-xmit tunnel push on subsequent packets without depending on uncontrollable timing or memory layout.\nPR:N - Exploitation requires only the ability to send network traffic through an already deployed IPIP-through-bridge flowtable offload path; no local account, authentication, or CAP_NET_ADMIN on the target is needed to trigger the crash.\nUI:N - No victim interaction is required beyond normal network traffic delivery; the attacker does not need the user to open files, mount filesystems, or perform any deliberate action.\nS:U - Impact is confined to kernel memory corruption and denial of service on the affected network namespace/host; it does not cross a VM, container, or IOMMU security boundary to compromise a separate authority.\nC:H - FLOW_OFFLOAD_XMIT_DIRECT stores MAC/ifindex data in a union aliasing dst_cache, so nf_flow_tunnel_ipip_push dereferences attacker-influenced bytes as a dst_entry/rtable, enabling uncontrolled kernel memory reads before the fault.\nI:H - The same invalid dst pointer drives skb_cow_head/headroom calculations and tunnel header writes in kernel transmit context, giving a plausible path to heap corruption and control-flow disruption beyond a simple NULL dereference.\nA:H - Invalid dst usage in the IPIP tunnel transmit path can cause kernel oops/panic or hard lockup when offloaded flows are exercised, fully denying availability of the affected system."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-17T05:41:59.975Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/0880c4ed122d0cddc9f29a2b28f055d1f24f0fca"
        },
        {
          "url": "https://git.kernel.org/stable/c/fa7395c02d95e51bad2952325d2d6503bfbad437"
        }
      ],
      "title": "netfilter: flowtable: support IPIP tunnel with direct xmit",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-72248",
    "datePublished": "2026-08-15T05:54:36.535Z",
    "dateReserved": "2026-08-09T03:40:39.914Z",
    "dateUpdated": "2026-08-17T05:41:59.975Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

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.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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