Vulnerability-Lookup

GHSA-H3C9-J2J5-6MFF

Vulnerability from github – Published: 2026-06-25 09:31 – Updated: 2026-06-28 09:31

Details

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.

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-2026-53221"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-06-25T09:16:39Z",
    "severity": "CRITICAL"
  },
  "details": "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.",
  "id": "GHSA-h3c9-j2j5-6mff",
  "modified": "2026-06-28T09:31:45Z",
  "published": "2026-06-25T09:31:21Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-53221"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/2abfb19bbb81958714ad1d43ebeb65b30394184b"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/2fc7bc087cc7085368263d9d37bfe9a0bddd6a2d"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/47fb3c2b4203556308e64354b3e78f2ce221d646"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/90fd4513315ca07da99cfd8549d3e553a7160f0d"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/a5c0359f5cbc51a2e2b114d6041e0f3c73f903e9"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/c327fa4fca31415431202e063767a7ae342e19c6"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f513f308cc4bdb4530d033431592ffbc29b7fca1"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/fc657ac0767c49839b3ef0b08dc0953ca30883f8"
    }
  ],
  "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-2026-53221 (GCVE-0-2026-53221)

Vulnerability from cvelistv5 – Published: 2026-06-25 08:39 – Updated: 2026-08-05 12:34

Title

ip6_vti: fix incorrect tunnel matching in vti6_tnl_lookup()

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.

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

8 references

URL	Tags
https://git.kernel.org/stable/c/c327fa4fca3141543…
https://git.kernel.org/stable/c/fc657ac0767c49839…
https://git.kernel.org/stable/c/47fb3c2b420355630…
https://git.kernel.org/stable/c/f513f308cc4bdb453…
https://git.kernel.org/stable/c/90fd4513315ca07da…
https://git.kernel.org/stable/c/2abfb19bbb8195871…
https://git.kernel.org/stable/c/2fc7bc087cc708536…
https://git.kernel.org/stable/c/a5c0359f5cbc51a2e…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: fbe68ee87522f6eaa10f9076c0a7117e1613f2f7 , < c327fa4fca31415431202e063767a7ae342e19c6 (git) Affected: fbe68ee87522f6eaa10f9076c0a7117e1613f2f7 , < fc657ac0767c49839b3ef0b08dc0953ca30883f8 (git) Affected: fbe68ee87522f6eaa10f9076c0a7117e1613f2f7 , < 47fb3c2b4203556308e64354b3e78f2ce221d646 (git) Affected: fbe68ee87522f6eaa10f9076c0a7117e1613f2f7 , < f513f308cc4bdb4530d033431592ffbc29b7fca1 (git) Affected: fbe68ee87522f6eaa10f9076c0a7117e1613f2f7 , < 90fd4513315ca07da99cfd8549d3e553a7160f0d (git) Affected: fbe68ee87522f6eaa10f9076c0a7117e1613f2f7 , < 2abfb19bbb81958714ad1d43ebeb65b30394184b (git) Affected: fbe68ee87522f6eaa10f9076c0a7117e1613f2f7 , < 2fc7bc087cc7085368263d9d37bfe9a0bddd6a2d (git) Affected: fbe68ee87522f6eaa10f9076c0a7117e1613f2f7 , < a5c0359f5cbc51a2e2b114d6041e0f3c73f903e9 (git)
Linux	Linux	Affected: 3.19 Unaffected: 0 , < 3.19 (semver) Unaffected: 5.10.259 , ≤ 5.10.* (semver) Unaffected: 5.15.210 , ≤ 5.15.* (semver) Unaffected: 6.1.176 , ≤ 6.1.* (semver) Unaffected: 6.6.143 , ≤ 6.6.* (semver) Unaffected: 6.12.94 , ≤ 6.12.* (semver) Unaffected: 6.18.36 , ≤ 6.18.* (semver) Unaffected: 7.0.13 , ≤ 7.0.* (semver) Unaffected: 7.1 , ≤ * (original_commit_for_fix)

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JSON

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/ipv6/ip6_vti.c"
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          "versions": [
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              "status": "affected",
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            },
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              "status": "affected",
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              "versionType": "git"
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              "versionType": "git"
            },
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              "version": "3.19"
            },
            {
              "lessThan": "3.19",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
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            {
              "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"
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              "status": "unaffected",
              "version": "6.6.143",
              "versionType": "semver"
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              "status": "unaffected",
              "version": "6.12.94",
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            },
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              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.36",
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            },
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              "lessThanOrEqual": "7.0.*",
              "status": "unaffected",
              "version": "7.0.13",
              "versionType": "semver"
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              "versionType": "original_commit_for_fix"
            }
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                  "vulnerable": true
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          "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."
        }
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              "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"
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        },
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        },
        {
          "url": "https://git.kernel.org/stable/c/a5c0359f5cbc51a2e2b114d6041e0f3c73f903e9"
        }
      ],
      "title": "ip6_vti: fix incorrect tunnel matching in vti6_tnl_lookup()",
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        "engine": "bippy-1.2.0"
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  "cveMetadata": {
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    "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"
}

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.
Browse all ATT&CK techniques and the vulnerabilities related to each.

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