{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-20959", "assignerOrgId": "f38d906d-7342-40ea-92c1-6c4a2c6478c8", "state": "PUBLISHED", "assignerShortName": "microsoft", "dateReserved": "2025-12-04T20:04:16.340Z", "datePublished": "2026-01-13T17:56:49.220Z", "dateUpdated": "2026-04-01T13:48:58.908Z"}, "containers": {"cna": {"title": "Microsoft SharePoint Server Spoofing Vulnerability", "datePublic": "2026-01-13T16:00:00.000Z", "cpeApplicability": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:microsoft:sharepoint_server_2016:*:*:*:*:enterprise:*:*:*", "versionStartIncluding": "16.0.0", "versionEndExcluding": "16.0.5535.1001"}, {"vulnerable": true, "criteria": "cpe:2.3:a:microsoft:sharepoint_server_2019:*:*:*:*:*:*:*:*", "versionStartIncluding": "16.0.0", "versionEndExcluding": "16.0.10417.20083"}, {"vulnerable": true, "criteria": "cpe:2.3:a:microsoft:sharepoint_server:*:*:*:*:subscription:*:*:*", "versionStartIncluding": "16.0.0", "versionEndExcluding": "16.0.19127.20442"}]}]}], "affected": [{"vendor": "Microsoft", "product": "Microsoft SharePoint Enterprise Server 2016", "platforms": ["x64-based Systems"], "versions": [{"version": "16.0.0", "lessThan": "16.0.5535.1001", "versionType": "custom", "status": "affected"}]}, {"vendor": "Microsoft", "product": "Microsoft SharePoint Server 2019", "platforms": ["x64-based Systems"], "versions": [{"version": "16.0.0", "lessThan": "16.0.10417.20083", "versionType": "custom", "status": "affected"}]}, {"vendor": "Microsoft", "product": "Microsoft SharePoint Server Subscription Edition", "platforms": ["x64-based Systems"], "versions": [{"version": "16.0.0", "lessThan": "16.0.19127.20442", "versionType": "custom", "status": "affected"}]}], "descriptions": [{"value": "Improper neutralization of input during web page generation ('cross-site scripting') in Microsoft Office SharePoint allows an authorized attacker to perform spoofing over a network.", "lang": "en-US"}], "problemTypes": [{"descriptions": [{"description": "CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')", "lang": "en-US", "type": "CWE", "cweId": "CWE-79"}]}], "providerMetadata": {"orgId": "f38d906d-7342-40ea-92c1-6c4a2c6478c8", "shortName": "microsoft", "dateUpdated": "2026-04-01T13:48:58.908Z"}, "references": [{"name": "Microsoft SharePoint Server Spoofing Vulnerability", "tags": ["vendor-advisory", "patch"], "url": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20959"}], "metrics": [{"format": "CVSS", "scenarios": [{"lang": "en-US", "value": "GENERAL"}], "cvssV3_1": {"version": "3.1", "baseSeverity": "MEDIUM", "baseScore": 4.6, "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N/E:U/RL:O/RC:C"}}]}, "adp": [{"metrics": [{"other": {"type": "ssvc", "content": {"timestamp": "2026-01-13T21:42:24.403689Z", "id": "CVE-2026-20959", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "partial"}], "role": "CISA Coordinator", "version": "2.0.3"}}}], "title": "CISA ADP Vulnrichment", "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-01-13T21:42:29.767Z"}}]}}

{"dataType": "CVE_RECORD", "containers": {"adp": [{"title": "CISA ADP Vulnrichment", "metrics": [{"other": {"type": "ssvc", "content": {"id": "CVE-2026-20959", "role": "CISA Coordinator", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "partial"}], "version": "2.0.3", "timestamp": "2026-01-13T21:42:24.403689Z"}}}], "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-01-13T21:42:27.414Z"}}], "cna": {"title": "Microsoft SharePoint Server Spoofing Vulnerability", "metrics": [{"format": "CVSS", "cvssV3_1": {"version": "3.1", "baseScore": 4.6, "baseSeverity": "MEDIUM", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N/E:U/RL:O/RC:C"}, "scenarios": [{"lang": "en-US", "value": "GENERAL"}]}], "affected": [{"vendor": "Microsoft", "product": "Microsoft SharePoint Enterprise Server 2016", "versions": [{"status": "affected", "version": "16.0.0", "lessThan": "16.0.5535.1001", "versionType": "custom"}], "platforms": ["x64-based Systems"]}, {"vendor": "Microsoft", "product": "Microsoft SharePoint Server 2019", "versions": [{"status": "affected", "version": "16.0.0", "lessThan": "16.0.10417.20083", "versionType": "custom"}], "platforms": ["x64-based Systems"]}, {"vendor": "Microsoft", "product": "Microsoft SharePoint Server Subscription Edition", "versions": [{"status": "affected", "version": "16.0.0", "lessThan": "16.0.19127.20442", "versionType": "custom"}], "platforms": ["x64-based Systems"]}], "datePublic": "2026-01-13T16:00:00.000Z", "references": [{"url": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20959", "name": "Microsoft SharePoint Server Spoofing Vulnerability", "tags": ["vendor-advisory", "patch"]}], "descriptions": [{"lang": "en-US", "value": "Improper neutralization of input during web page generation ('cross-site scripting') in Microsoft Office SharePoint allows an authorized attacker to perform spoofing over a network."}], "problemTypes": [{"descriptions": [{"lang": "en-US", "type": "CWE", "cweId": "CWE-79", "description": "CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')"}]}], "cpeApplicability": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:a:microsoft:sharepoint_server_2016:*:*:*:*:enterprise:*:*:*", "vulnerable": true, "versionEndExcluding": "16.0.5535.1001", "versionStartIncluding": "16.0.0"}, {"criteria": "cpe:2.3:a:microsoft:sharepoint_server_2019:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "16.0.10417.20083", "versionStartIncluding": "16.0.0"}, {"criteria": "cpe:2.3:a:microsoft:sharepoint_server:*:*:*:*:subscription:*:*:*", "vulnerable": true, "versionEndExcluding": "16.0.19127.20442", "versionStartIncluding": "16.0.0"}], "operator": "OR"}]}], "providerMetadata": {"orgId": "f38d906d-7342-40ea-92c1-6c4a2c6478c8", "shortName": "microsoft", "dateUpdated": "2026-04-01T13:48:58.908Z"}}}, "cveMetadata": {"cveId": "CVE-2026-20959", "state": "PUBLISHED", "dateUpdated": "2026-04-01T13:48:58.908Z", "dateReserved": "2025-12-04T20:04:16.340Z", "assignerOrgId": "f38d906d-7342-40ea-92c1-6c4a2c6478c8", "datePublished": "2026-01-13T17:56:49.220Z", "assignerShortName": "microsoft"}, "dataVersion": "5.2"}

{"configurations": [{"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:a:microsoft:sharepoint_server:*:*:*:*:subscription:*:*:*", "matchCriteriaId": "FB9ECA81-C1E2-4B02-A45C-0E5664E3C9B9", "versionEndExcluding": "16.0.19127.20442", "vulnerable": true}, {"criteria": "cpe:2.3:a:microsoft:sharepoint_server:2016:*:*:*:enterprise:*:*:*", "matchCriteriaId": "F815EF1D-7B60-47BE-9AC2-2548F99F10E4", "vulnerable": true}, {"criteria": "cpe:2.3:a:microsoft:sharepoint_server:2019:*:*:*:*:*:*:*", "matchCriteriaId": "6122D014-5BF1-4AF4-8B4D-80205ED7785E", "vulnerable": true}], "negate": false, "operator": "OR"}]}], "cveTags": [], "descriptions": [{"lang": "en", "value": "Improper neutralization of input during web page generation ('cross-site scripting') in Microsoft Office SharePoint allows an authorized attacker to perform spoofing over a network."}], "id": "CVE-2026-20959", "lastModified": "2026-01-14T19:19:39.877", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 4.6, "baseSeverity": "MEDIUM", "confidentialityImpact": "LOW", "integrityImpact": "LOW", "privilegesRequired": "LOW", "scope": "UNCHANGED", "userInteraction": "REQUIRED", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N", "version": "3.1"}, "exploitabilityScore": 2.1, "impactScore": 2.5, "source": "secure@microsoft.com", "type": "Secondary"}, {"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 5.4, "baseSeverity": "MEDIUM", "confidentialityImpact": "LOW", "integrityImpact": "LOW", "privilegesRequired": "LOW", "scope": "CHANGED", "userInteraction": "REQUIRED", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N", "version": "3.1"}, "exploitabilityScore": 2.3, "impactScore": 2.7, "source": "nvd@nist.gov", "type": "Primary"}]}, "published": "2026-01-13T18:16:23.937", "references": [{"source": "secure@microsoft.com", "tags": ["Vendor Advisory"], "url": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20959"}], "sourceIdentifier": "secure@microsoft.com", "vulnStatus": "Analyzed", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-79"}], "source": "secure@microsoft.com", "type": "Primary"}]}

{}

{"analysis": {"en": {"generated_at": "2026-04-16T18:14:44.107724+00:00", "value": {"mitigation_remediation": ["Download and install the Microsoft security update for SharePoint from the advisory link (https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20959).", "Limit page authoring permissions so that only trusted users can modify content that appears on public or shared sites.", "Configure a Content Security Policy (CSP) and enable SharePoint\u2019s built\u2011in script and input validation controls to mitigate injection of malicious HTML or JavaScript."], "summary": {"action": "Apply Patch", "impact": "Spoofing via XSS"}, "threat_synthesis": {"affected_systems": "Microsoft SharePoint Enterprise Server 2016, Microsoft SharePoint Server 2019, and Microsoft SharePoint Server Subscription Edition are affected. No specific version details are listed beyond the product names, indicating that multiple releases within these product lines may be vulnerable.", "description_and_impact": "Improper neutralization of input during web page generation in Microsoft SharePoint enables cross\u2011site scripting that can cause a malicious site to appear authentic to users. The vulnerability allows an authorized attacker to inject content that is rendered as part of the SharePoint interface, enabling spoofing across the network. This can lead to users believing that an attacker\u2019s content is coming from the legitimate SharePoint system, potentially enabling further deception or phishing attacks. The weakness is a classic cross\u2011site scripting flaw classified as CWE\u201179.", "risk_and_exploitability": "The CVSS score of 4.6 classifies the severity as moderate, while the EPSS score of less than 1% suggests a very low likelihood of exploitation at present. The vulnerability is not listed in the CISA KEV catalog. The attack requires an attacker to already possess authorized access to the SharePoint environment; there is no indication that a publicly exposed exploitation pathway exists. Therefore, insiders or compromised accounts are the primary threat vector, and the risk is amplified where privileged users can manipulate web content."}}}}, "created": "2026-04-16T18:15:43.301640+00:00", "updated": "2026-04-16T18:15:43.301651+00:00", "vendors": []}