CVE-2026-97965 (GCVE-0-2026-97965)
Vulnerability from cvelistv5
Published
2026-09-25 10:23
Modified
2026-10-21 12:53
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: vxlan: initialize _md in vxlan_xmit_one() If a VXLAN device is configured with both VXLAN_F_COLLECT_METADATA and VXLAN_F_GBP, and a packet is transmitted through it using an external ip_tunnel_info that lacks the IP_TUNNEL_VXLAN_OPT_BIT flag, md is left pointing to the uninitialized _md stack variable: if (test_bit(IP_TUNNEL_VXLAN_OPT_BIT, info->key.tun_flags)) { if (info->options_len < sizeof(*md)) goto drop; md = ip_tunnel_info_opts(info); } Because IP_TUNNEL_VXLAN_OPT_BIT is not set, md is not updated and remains pointing to _md. Later, vxlan_build_skb() is called with md, which eventually calls vxlan_build_gbp_hdr(): if (vxflags & VXLAN_F_GBP) vxlan_build_gbp_hdr(vxh, md); Inside vxlan_build_gbp_hdr(), md->gbp is read: if (!md->gbp) return; gbp = (struct vxlanhdr_gbp *)vxh; ... if (md->gbp & VXLAN_GBP_DONT_LEARN) gbp->dont_learn = 1; If the stack contains garbage, this causes: 1) VXLAN_HF_GBP flag to be spuriously set in the VXLAN header. 2) gbp->dont_learn and gbp->policy_applied to be set from stack bits. 3) gbp->policy_id to receive 16 bits of uninitialized kernel stack data, leaking it onto the wire. Fix this by zero-initializing _md. If IP_TUNNEL_VXLAN_OPT_BIT is not present, md->gbp remains 0, and vxlan_build_gbp_hdr() returns early without modifying the VXLAN header.
References
Impacted products
Vendor Product Version
Linux Linux Version: ee122c79d4227f6ec642157834b6a90fcffa4382
Version: ee122c79d4227f6ec642157834b6a90fcffa4382
Version: ee122c79d4227f6ec642157834b6a90fcffa4382
Version: ee122c79d4227f6ec642157834b6a90fcffa4382
Version: ee122c79d4227f6ec642157834b6a90fcffa4382
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/net/vxlan/vxlan_core.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
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          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "drivers/net/vxlan/vxlan_core.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "4.3"
            },
            {
              "lessThan": "4.3",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
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              "status": "unaffected",
              "version": "6.6.160",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.111",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.53",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.7",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.160",
                  "versionStartIncluding": "4.3",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.111",
                  "versionStartIncluding": "4.3",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.53",
                  "versionStartIncluding": "4.3",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.7",
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                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3",
                  "versionStartIncluding": "4.3",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nvxlan: initialize _md in vxlan_xmit_one()\n\nIf a VXLAN device is configured with both VXLAN_F_COLLECT_METADATA and\nVXLAN_F_GBP, and a packet is transmitted through it using an external\nip_tunnel_info that lacks the IP_TUNNEL_VXLAN_OPT_BIT flag, md is left\npointing to the uninitialized _md stack variable:\n\n                if (test_bit(IP_TUNNEL_VXLAN_OPT_BIT, info-\u003ekey.tun_flags)) {\n                        if (info-\u003eoptions_len \u003c sizeof(*md))\n                                goto drop;\n                        md = ip_tunnel_info_opts(info);\n                }\n\nBecause IP_TUNNEL_VXLAN_OPT_BIT is not set, md is not updated and remains\npointing to _md. Later, vxlan_build_skb() is called with md, which\neventually calls vxlan_build_gbp_hdr():\n\n        if (vxflags \u0026 VXLAN_F_GBP)\n                vxlan_build_gbp_hdr(vxh, md);\n\nInside vxlan_build_gbp_hdr(), md-\u003egbp is read:\n\n        if (!md-\u003egbp)\n                return;\n        gbp = (struct vxlanhdr_gbp *)vxh;\n        ...\n        if (md-\u003egbp \u0026 VXLAN_GBP_DONT_LEARN)\n                gbp-\u003edont_learn = 1;\n\nIf the stack contains garbage, this causes:\n1) VXLAN_HF_GBP flag to be spuriously set in the VXLAN header.\n2) gbp-\u003edont_learn and gbp-\u003epolicy_applied to be set from stack bits.\n3) gbp-\u003epolicy_id to receive 16 bits of uninitialized kernel stack data,\n   leaking it onto the wire.\n\nFix this by zero-initializing _md. If IP_TUNNEL_VXLAN_OPT_BIT is not\npresent, md-\u003egbp remains 0, and vxlan_build_gbp_hdr() returns early\nwithout modifying the VXLAN header."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-21T12:53:54.233Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/fb78beb64e0e79557e4cd7cd17fea744bb6f01d9"
        },
        {
          "url": "https://git.kernel.org/stable/c/0d13b5a413bffc8718b3821b78537ccc6596c233"
        },
        {
          "url": "https://git.kernel.org/stable/c/bfb74c48ac2d31476d5e09cf9658844508d2608a"
        },
        {
          "url": "https://git.kernel.org/stable/c/081f22177d9d12b1e381b787f203cd5f47508187"
        },
        {
          "url": "https://git.kernel.org/stable/c/be83178bfc44588f6e3adb827ed874c683193466"
        }
      ],
      "title": "vxlan: initialize _md in vxlan_xmit_one()",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-97965",
    "datePublished": "2026-09-25T10:23:07.952Z",
    "dateReserved": "2026-09-25T10:18:58.206Z",
    "dateUpdated": "2026-10-21T12:53:54.233Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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