{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-21218", "assignerOrgId": "f38d906d-7342-40ea-92c1-6c4a2c6478c8", "state": "PUBLISHED", "assignerShortName": "microsoft", "dateReserved": "2025-12-11T21:02:05.731Z", "datePublished": "2026-02-10T17:51:23.973Z", "dateUpdated": "2026-02-10T20:38:27.365Z"}, "containers": {"cna": {"title": ".NET Spoofing Vulnerability", "datePublic": "2026-02-10T08:00:00.000Z", "cpeApplicability": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:microsoft:.net:*:*:*:*:*:*:*:*", "versionStartIncluding": "10.0.0", "versionEndExcluding": "10.0.3"}, {"vulnerable": true, "criteria": "cpe:2.3:a:microsoft:.net:*:*:*:*:*:*:*:*", "versionStartIncluding": "8.0.0", "versionEndExcluding": "8.0.24"}, {"vulnerable": true, "criteria": "cpe:2.3:a:microsoft:.net:*:*:*:*:*:*:*:*", "versionStartIncluding": "9.0.0", "versionEndExcluding": "9.0.13"}]}]}], "affected": [{"vendor": "Microsoft", "product": ".NET 10.0", "versions": [{"version": "10.0.0", "lessThan": "10.0.3", "versionType": "custom", "status": "affected"}]}, {"vendor": "Microsoft", "product": ".NET 8.0", "versions": [{"version": "8.0.0", "lessThan": "8.0.24", "versionType": "custom", "status": "affected"}]}, {"vendor": "Microsoft", "product": ".NET 9.0", "versions": [{"version": "9.0.0", "lessThan": "9.0.13", "versionType": "custom", "status": "affected"}]}], "descriptions": [{"value": "Improper handling of missing special element in .NET allows an unauthorized attacker to perform spoofing over a network.", "lang": "en-US"}], "problemTypes": [{"descriptions": [{"description": "CWE-166: Improper Handling of Missing Special Element", "lang": "en-US", "type": "CWE", "cweId": "CWE-166"}]}], "providerMetadata": {"orgId": "f38d906d-7342-40ea-92c1-6c4a2c6478c8", "shortName": "microsoft", "dateUpdated": "2026-02-10T20:38:27.365Z"}, "references": [{"name": ".NET Spoofing Vulnerability", "tags": ["vendor-advisory", "patch"], "url": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21218"}], "metrics": [{"format": "CVSS", "scenarios": [{"lang": "en-US", "value": "GENERAL"}], "cvssV3_1": {"version": "3.1", "baseSeverity": "HIGH", "baseScore": 7.5, "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N/E:U/RL:O/RC:C"}}]}}}

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{"cveTags": [], "descriptions": [{"lang": "en", "value": "Improper handling of missing special element in .NET allows an unauthorized attacker to perform spoofing over a network."}], "id": "CVE-2026-21218", "lastModified": "2026-02-10T18:16:22.967", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 7.5, "baseSeverity": "HIGH", "confidentialityImpact": "NONE", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N", "version": "3.1"}, "exploitabilityScore": 3.9, "impactScore": 3.6, "source": "secure@microsoft.com", "type": "Primary"}]}, "published": "2026-02-10T18:16:22.967", "references": [{"source": "secure@microsoft.com", "url": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21218"}], "sourceIdentifier": "secure@microsoft.com", "vulnStatus": "Received", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-166"}], "source": "secure@microsoft.com", "type": "Primary"}]}

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