{"id":"CVE-2026-20963","published":"2026-01-13T18:16:24Z","modified":"2026-06-17T10:18:07Z","title":"Microsoft SharePoint Deserialization of Untrusted Data Vulnerability","vendor":"Microsoft","product":"SharePoint","tier":"core","eol":null,"description":{"text":"Deserialization of untrusted data in Microsoft Office SharePoint allows an unauthorized attacker to execute code over a network.","provenance":"source","from":"NVD"},"summary":{"text":"A deserialization of untrusted data flaw exists in Microsoft Office SharePoint, a Microsoft SharePoint product component. An unauthorized attacker can execute code over a network, with no authentication or user interaction required.","provenance":"ai","model":"claude-haiku-5-5","generatedAt":"2026-10-23T07:12:08Z"},"cvss":{"score":9.8,"severity":"CRITICAL","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","provenance":"source","from":"NVD"},"epss":{"score":0.29201,"percentile":0.98169,"date":"2026-10-30","provenance":"source"},"kev":{"dateAdded":"2026-03-18","dueDate":"2026-03-21","ransomware":false,"requiredAction":"Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.","notes":"https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20963 ; https://nvd.nist.gov/vuln/detail/CVE-2026-20963","provenance":"source"},"vulncheckKev":{"dateAdded":"2026-03-18","exploitedFirstSeen":"2026-03-18","ransomware":false,"evidence":[{"url":"https://www.cisa.gov/sites/default/files/feeds/known_exploited_vulnerabilities.json","date":"2026-03-18"},{"url":"https://www.recordedfuture.com/blog/march-2026-cve-landscape","date":"2026-04-13"},{"url":"https://cyble.com/blog/monthly-threat-landscape-march-2026/","date":"2026-04-20"},{"url":"https://thecyberexpress.com/march-2026-threat-landscape/","date":"2026-04-22"},{"url":"https://www.tenable.com/blog/cve-2026-32201-cve-2026-45659-cve-2026-56164-faq-sharepoint-server-exploitation","date":"2026-07-16"},{"url":"https://cyble.com/reports/H1-2026-Global-Threat-Landscape-Report.pdf","date":"2026-07-27"}],"evidenceTotal":6,"provenance":"source"},"exploited":true,"otx":{"pulseCount":50,"pulses":[{"name":"Actively_Exploited_Kev | Oct 31, 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2026","url":"https://otx.alienvault.com/pulse/6ad8d33a077cbb5cab524d80","created":"2026-10-21"},{"name":"Actively_Exploited_Kev | Oct 21, 2026","url":"https://otx.alienvault.com/pulse/6ad78130c4d1ac2be83a8b6d","created":"2026-10-20"},{"name":"Actively_Exploited_Kev | Oct 20, 2026","url":"https://otx.alienvault.com/pulse/6ad62f63c24a405a3423cc13","created":"2026-10-19"}],"provenance":"machine"},"cwes":[{"id":"CWE-502","name":"Deserialization of Untrusted Data"}],"references":[{"url":"https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20963","tags":["Vendor Advisory"]},{"url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-20963","tags":["US Government Resource"]}],"techniques":[{"id":"T1190","name":"Exploit Public-Facing Application","tactics":["initial-access"],"provenance":"ai","basis":"ai-mapping","bases":["ai-mapping"],"basisDetail":"claude-haiku-5-5: unauthenticated network exploitation of public-facing SharePoint","mappingType":"exploitation_technique","evidence":[{"from":"description","quote":"allows an unauthorized attacker to execute code over a network","start":65,"end":127}],"model":"claude-haiku-5-5","confidence":"medium","confidenceNote":"AI-mapped from the description (quote-validated, not expert-reviewed)"},{"id":"T1059","name":"Command and Scripting Interpreter","tactics":["execution"],"provenance":"ai","basis":"ai-mapping","bases":["ai-mapping"],"basisDetail":"claude-haiku-5-5: deserialization yields arbitrary code execution","mappingType":"primary_impact","evidence":[{"from":"description","quote":"allows an unauthorized attacker to execute code over a network","start":65,"end":127}],"model":"claude-haiku-5-5","confidence":"medium","confidenceNote":"AI-mapped from the description (quote-validated, not expert-reviewed)"}],"reports":[],"affected":[],"advisories":[],"euvd":{"id":"EUVD-2026-2114","url":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-2114","exploited":true,"exploitedSince":"2026-03-12","provenance":"source"},"exploits":[],"exploitSources":null,"exploitRefs":[],"flow":[{"stage":"exploitation","techniques":["T1190"],"provenance":"ai"},{"stage":"primary","techniques":["T1059"],"provenance":"ai"}],"timeline":[{"date":"2026-01-13","kind":"published","label":"Published (NVD)","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-20963","provenance":"source"},{"date":"2026-03-12","kind":"euvd-exploited","label":"ENISA EUVD: exploited","url":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-2114","provenance":"source"},{"date":"2026-03-18","kind":"exploited-reported","label":"Exploitation first reported (VulnCheck KEV 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product","points":0.0,"detail":"supported or unknown"}]},"lineage":{"familyId":"fam-class-microsoft-sharepoint-cwe-502"}}