CVE-2026-53221 (GCVE-0-2026-53221)
Vulnerability from cvelistv5
Published
2026-06-25 08:39
Modified
2026-08-05 12:34
Severity ?
9.8 (Critical) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: ip6_vti: fix incorrect tunnel matching in vti6_tnl_lookup() In vti6_tnl_lookup(), when an exact match for a tunnel fails, the code falls back to searching for wildcard tunnels: - Tunnels matching the packet's local address, with any remote address wildcard remote). - Tunnels matching the packet's remote address, with any local address (wildcard local). However, vti6 stores all these different types of tunnels in the same hash table (ip6n->tnls_r_l) prone to hash collisions. The bug is that the fallback search loops in vti6_tnl_lookup() were missing checks to ensure that the candidate tunnel actually has a wildcard address.
References
Impacted products
Vendor Product Version
Linux Linux Version: fbe68ee87522f6eaa10f9076c0a7117e1613f2f7
Version: fbe68ee87522f6eaa10f9076c0a7117e1613f2f7
Version: fbe68ee87522f6eaa10f9076c0a7117e1613f2f7
Version: fbe68ee87522f6eaa10f9076c0a7117e1613f2f7
Version: fbe68ee87522f6eaa10f9076c0a7117e1613f2f7
Version: fbe68ee87522f6eaa10f9076c0a7117e1613f2f7
Version: fbe68ee87522f6eaa10f9076c0a7117e1613f2f7
Version: fbe68ee87522f6eaa10f9076c0a7117e1613f2f7
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/ipv6/ip6_vti.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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              "status": "affected",
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          "product": "Linux",
          "programFiles": [
            "net/ipv6/ip6_vti.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "3.19"
            },
            {
              "lessThan": "3.19",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.10.*",
              "status": "unaffected",
              "version": "5.10.259",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.210",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.176",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.143",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.94",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.36",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.0.*",
              "status": "unaffected",
              "version": "7.0.13",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.10.259",
                  "versionStartIncluding": "3.19",
                  "vulnerable": true
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                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.15.210",
                  "versionStartIncluding": "3.19",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.1.176",
                  "versionStartIncluding": "3.19",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.143",
                  "versionStartIncluding": "3.19",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                  "versionStartIncluding": "3.19",
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                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                  "versionStartIncluding": "3.19",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.0.13",
                  "versionStartIncluding": "3.19",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.1",
                  "versionStartIncluding": "3.19",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nip6_vti: fix incorrect tunnel matching in vti6_tnl_lookup()\n\nIn vti6_tnl_lookup(), when an exact match for a tunnel fails,\nthe code falls back to searching for wildcard tunnels:\n\n- Tunnels matching the packet\u0027s local address, with any remote address\n  wildcard remote).\n\n- Tunnels matching the packet\u0027s remote address, with any local address\n  (wildcard local).\n\nHowever, vti6 stores all these different types of tunnels in the same\nhash table (ip6n-\u003etnls_r_l) prone to hash collisions.\n\nThe bug is that the fallback search loops in vti6_tnl_lookup() were\nmissing checks to ensure that the candidate tunnel actually has\na wildcard address."
        }
      ],
      "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 vulnerable lookup is reached from IPv6 packet input through registered XFRM ESP/AH/IPComp and IP-in-IPv6 tunnel handlers, so a remote peer can trigger it with network traffic.\nAC:L - The bug is a deterministic missing wildcard-address check in a small hash table; once a plausible VTI6 configuration with colliding wildcard/exact tunnel entries exists, chosen packets reliably exercise the wrong lookup.\nPR:N - The packet receive path reaches `vti6_tnl_lookup()` before any per-packet authentication succeeds, and no local privilege is needed to send the triggering IPv6 traffic.\nUI:N - No victim user action is required; packets are processed by the kernel networking receive path.\nS:U - The impact remains within the kernel/networking security authority and does not by itself cross a VM, IOMMU, or host boundary.\nC:H - Wrong tunnel selection can associate decapsulated traffic with another VTI device, mark, and policy context; in a multi-tenant IPsec/VTI gateway this can expose tunneled plaintext across tunnel boundaries.\nI:H - The same confusion can deliver attacker-controlled inner packets under the wrong tunnel interface and policy context, enabling unauthorized modification or injection of traffic in the affected tunnel domain.\nA:H - Incorrect matching can consistently drop or misprocess traffic for affected tunnels, allowing loss of availability of the VTI/IPsec connectivity in vulnerable configurations."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:34:14.672Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/c327fa4fca31415431202e063767a7ae342e19c6"
        },
        {
          "url": "https://git.kernel.org/stable/c/fc657ac0767c49839b3ef0b08dc0953ca30883f8"
        },
        {
          "url": "https://git.kernel.org/stable/c/47fb3c2b4203556308e64354b3e78f2ce221d646"
        },
        {
          "url": "https://git.kernel.org/stable/c/f513f308cc4bdb4530d033431592ffbc29b7fca1"
        },
        {
          "url": "https://git.kernel.org/stable/c/90fd4513315ca07da99cfd8549d3e553a7160f0d"
        },
        {
          "url": "https://git.kernel.org/stable/c/2abfb19bbb81958714ad1d43ebeb65b30394184b"
        },
        {
          "url": "https://git.kernel.org/stable/c/2fc7bc087cc7085368263d9d37bfe9a0bddd6a2d"
        },
        {
          "url": "https://git.kernel.org/stable/c/a5c0359f5cbc51a2e2b114d6041e0f3c73f903e9"
        }
      ],
      "title": "ip6_vti: fix incorrect tunnel matching in vti6_tnl_lookup()",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-53221",
    "datePublished": "2026-06-25T08:39:23.177Z",
    "dateReserved": "2026-06-09T07:44:35.392Z",
    "dateUpdated": "2026-08-05T12:34:14.672Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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