ip-address: isInSubnet() and isHostInSubnet() compare addresses of different families as if they shared an address space, allowing an allowlist check to admit an address outside its range

{
  "id": "a5c77212113a8f2af34b6d68aa698ea2b1937344a38009ed08e1d02e4a147194",
  "url": "https://osv.dev/vulnerability/CVE-2026-101912",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "ip-address: isInSubnet() and isHostInSubnet() compare addresses of different families as if they shared an address space, allowing an allowlist check to admit an address outside its range",
    "summary": "ip-address is a library for parsing and manipulating IPv4 and IPv6 addresses in JavaScript. Prior to 10.7.1, the isInSubnet and isHostInSubnet methods in src/common.ts compare masked binary strings without validating that both operands use the same IP family. A cross-family containment check whose leading address bits match makes the masked strings compare equal even though IPv4 and IPv6 do not share an address space. An allowlist or denylist decision can therefore classify an address outside the intended range as contained. This issue is fixed in version 10.7.1.",
    "evidence": "osv:CVE-2026-101912",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2026-101912",
      "aliases": [
        "CVE-2026-101912",
        "GHSA-j6r3-76f7-8jcv"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/beaugunderson/ip-address",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "f0c25dfd4fbf7886e45116ba0940207f81401e28"
                },
                {
                  "fixed": "1343629d57fea413644a5c9d41ff1e59619f3f28"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "10.7.1"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StringRangeExpression"
                  },
                  {
                    "range": [
                      {
                        "fixed": "1343629d57fea413644a5c9d41ff1e59619f3f28"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  },
                  {
                    "range": [
                      {
                        "fixed": "f0c25dfd4fbf7886e45116ba0940207f81401e28"
                      }
                    ],
                    "source": "REFERENCES_TAG",
                    "original_tag": "v10.7.1"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v10.7.0",
            "v10.6.0",
            "v10.5.1",
            "v10.5.0",
            "v10.4.0",
            "v10.3.1",
            "v10.3.0",
            "v10.2.2",
            "v10.2.1",
            "v10.2.0",
            "v10.1.1",
            "v10.1.0",
            "v10.0.1",
            "v10.0.0",
            "v9.1.0-0",
            "v9.0.5",
            "v9.0.3",
            "v9.0.2",
            "v9.0.1",
            "v9.0.0",
            "v8.1.0",
            "v8.0.0",
            "v7.1.0",
            "v7.0.1",
            "v7.0.0",
            "v6.4.0",
            "v6.3.0",
            "v6.2.0",
            "v6.1.0",
            "v6.0.0",
            "v5.9.4",
            "v5.9.3",
            "v5.9.2",
            "v5.9.1",
            "v5.9.0",
            "v5.8.9",
            "v5.8.8",
            "v5.8.7",
            "v5.8.6",
            "v5.8.5",
            "v5.8.4",
            "v5.8.3",
            "v5.8.2",
            "v5.8.1",
            "v5.8.0",
            "v5.7.0",
            "v5.6.0",
            "v5.5.0",
            "v5.4.1",
            "v5.4.0",
            "v5.3.0",
            "v5.2.0",
            "v3.1.0",
            "v2.0.2",
            "v2.0.1",
            "2.0.0",
            "1.1.0",
            "1.0.0"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-101912.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:26.141892086Z",
      "provider": "osv",
      "references": [
        "https://github.com/beaugunderson/ip-address/releases/tag/v10.7.1",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/101xxx/CVE-2026-101912.json",
        "https://github.com/beaugunderson/ip-address/security/advisories/GHSA-j6r3-76f7-8jcv",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-101912",
        "https://github.com/beaugunderson/ip-address/commit/1343629d57fea413644a5c9d41ff1e59619f3f28"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-697",
          "CWE-843"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/101xxx/CVE-2026-101912.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-101912",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 492896,
  "published_at": "2026-09-28T17:48:06.99+00:00"
}