CVE-1999-1087

Status: ModifiedHigh (7.5)—

Internet Explorer 4 treats a 32-bit number ("dotless IP address") in the a URL as the hostname instead of an IP address, which causes IE to apply Local Intranet Zone settings to the resulting web page, allowing remote malicious web servers to conduct unauthorized activities by using URLs that contain the dotless IP address for their server.

CVSS

Version: 2.0
Vector: AV:N/AC:L/Au:N/C:P/I:P/A:P
Base score: 7.5

Exploitation probability (EPSS)

Probability of exploitation in the next 30 days: 6.40%
Percentile among all scored CVEs: 94
Score date: 10/9/2026

EPSS (Exploit Prediction Scoring System, FIRST) estimates how likely a vulnerability is to be exploited in the wild within 30 days. It complements CVSS (impact) and CISA KEV (confirmed exploitation).

Affected technologies (1)

Microsoft — Internet Explorer

CWEs

NVD-CWE-Other

References

Raw JSON (NVD)

Show

{
  "id": "CVE-1999-1087",
  "cveTags": [],
  "metrics": {
    "cvssMetricV2": [
      {
        "type": "Primary",
        "source": "nvd@nist.gov",
        "cvssData": {
          "version": "2.0",
          "baseScore": 7.5,
          "accessVector": "NETWORK",
          "vectorString": "AV:N/AC:L/Au:N/C:P/I:P/A:P",
          "authentication": "NONE",
          "integrityImpact": "PARTIAL",
          "accessComplexity": "LOW",
          "availabilityImpact": "PARTIAL",
          "confidentialityImpact": "PARTIAL"
        },
        "acInsufInfo": false,
        "impactScore": 6.4,
        "baseSeverity": "HIGH",
        "obtainAllPrivilege": false,
        "exploitabilityScore": 10,
        "obtainUserPrivilege": false,
        "obtainOtherPrivilege": false,
        "userInteractionRequired": false
      }
    ]
  },
  "affected": [
    {
      "source": "cve@mitre.org",
      "affectedData": [
        {
          "vendor": "n/a",
          "product": "n/a",
          "versions": [
            {
              "status": "affected",
              "version": "n/a"
            }
          ]
        }
      ]
    }
  ],
  "published": "1999-12-31T05:00:00.000",
  "references": [
    {
      "url": "http://support.microsoft.com/support/kb/articles/q168/6/17.asp",
      "tags": [
        "Patch",
        "Vendor Advisory"
      ],
      "source": "cve@mitre.org"
    },
    {
      "url": "http://www.microsoft.com/Windows/Ie/security/dotless.asp",
      "source": "cve@mitre.org"
    },
    {
      "url": "http://www.osvdb.org/7828",
      "source": "cve@mitre.org"
    },
    {
      "url": "https://docs.microsoft.com/en-us/security-updates/securitybulletins/1998/ms98-016",
      "source": "cve@mitre.org"
    },
    {
      "url": "https://exchange.xforce.ibmcloud.com/vulnerabilities/2209",
      "source": "cve@mitre.org"
    },
    {
      "url": "http://support.microsoft.com/support/kb/articles/q168/6/17.asp",
      "tags": [
        "Patch",
        "Vendor Advisory"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "http://www.microsoft.com/Windows/Ie/security/dotless.asp",
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "http://www.osvdb.org/7828",
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "https://docs.microsoft.com/en-us/security-updates/securitybulletins/1998/ms98-016",
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "https://exchange.xforce.ibmcloud.com/vulnerabilities/2209",
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    }
  ],
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "type": "Primary",
      "source": "nvd@nist.gov",
      "description": [
        {
          "lang": "en",
          "value": "NVD-CWE-Other"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "Internet Explorer 4 treats a 32-bit number (\"dotless IP address\") in the a URL as the hostname instead of an IP address, which causes IE to apply Local Intranet Zone settings to the resulting web page, allowing remote malicious web servers to conduct unauthorized activities by using URLs that contain the dotless IP address for their server."
    }
  ],
  "lastModified": "2026-06-16T21:49:41.647",
  "configurations": [
    {
      "nodes": [
        {
          "negate": false,
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:microsoft:internet_explorer:4.0:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "A5B815D9-BC21-4A17-AF00-B8AD181027D7"
            },
            {
              "criteria": "cpe:2.3:a:microsoft:internet_explorer:4.0.1:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "42502347-DD40-4F8C-9861-C0A88A3F8608"
            },
            {
              "criteria": "cpe:2.3:a:microsoft:internet_explorer:4.0.1:sp1:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "0AF9C64F-9A67-4BA9-A653-75507935E6EA"
            }
          ],
          "operator": "OR"
        }
      ]
    }
  ],
  "sourceIdentifier": "cve@mitre.org"
}