{"id":"CVE-2026-50522","published":"2026-07-14T17:17:01Z","modified":"2026-07-23T15:44:10Z","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":"Microsoft SharePoint contains a deserialization of untrusted data flaw in its Microsoft Office SharePoint component, which handles how the product processes serialized input. An unauthorized attacker with network access can exploit it to execute code, requiring no authentication, no user interaction, and no particular configuration.","provenance":"ai","model":"claude-haiku-5-5","generatedAt":"2026-10-23T07:13:33Z"},"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":0.03042,"percentile":0.87509,"date":"2026-10-30","provenance":"source"},"kev":{"dateAdded":"2026-07-22","dueDate":"2026-07-25","ransomware":false,"requiredAction":"Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.","notes":"https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-50522 ; BOD 26-04: https://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk ; Forensics Triage Requirements: https://www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk ; https://nvd.nist.gov/vuln/detail/CVE-2026-50522","provenance":"source"},"vulncheckKev":{"dateAdded":"2026-07-20","exploitedFirstSeen":"2026-07-20","ransomware":false,"evidence":[{"url":"https://x.com/DefusedCyber/status/2079128402855116858","date":"2026-07-20"},{"url":"https://previdian.com/CVE-2026-50522","date":"2026-07-21"},{"url":"https://www.linkedin.com/posts/exploitation-alert-watchtowr-is-observing-share-7485278592730333184-rV0l/","date":"2026-07-21"},{"url":"https://www.cisa.gov/sites/default/files/feeds/known_exploited_vulnerabilities.json","date":"2026-07-22"},{"url":"https://blog.hunterstrategy.net/the-convenience-problem/","date":"2026-07-24"},{"url":"https://www.recordedfuture.com/blog/july-2026-cve-landscape","date":"2026-08-07"},{"url":"https://dashboard.shadowserver.org/statistics/honeypot/vulnerability/map/?day=2026-08-16&host_type=src&vulnerability=cve-2026-50522","date":"2026-08-16"},{"url":"https://dashboard.shadowserver.org/statistics/honeypot/vulnerability/map/?day=2026-08-17&host_type=src&vulnerability=cve-2026-50522","date":"2026-08-17"},{"url":"https://dashboard.shadowserver.org/statistics/honeypot/vulnerability/map/?day=2026-08-18&host_type=src&vulnerability=cve-2026-50522","date":"2026-08-18"},{"url":"https://dashboard.shadowserver.org/statistics/honeypot/vulnerability/map/?day=2026-08-19&host_type=src&vulnerability=cve-2026-50522","date":"2026-08-19"}],"evidenceTotal":48,"provenance":"source"},"exploited":true,"otx":{"pulseCount":50,"pulses":[{"name":"Actively_Exploited_Kev | Oct 31, 2026","url":"https://otx.alienvault.com/pulse/6ae4aefab0c2191cecd41862","created":"2026-10-30"},{"name":"Actively_Exploited_Kev | Oct 30, 2026","url":"https://otx.alienvault.com/pulse/6ae35d889ea92b4ce19c2680","created":"2026-10-29"},{"name":"Actively_Exploited_Kev | Oct 29, 2026","url":"https://otx.alienvault.com/pulse/6ae20c1db17e7057ae7d9ad1","created":"2026-10-28"},{"name":"Actively_Exploited_Kev | Oct 28, 2026","url":"https://otx.alienvault.com/pulse/6ae0ba7e0e2a97ff7b218819","created":"2026-10-27"},{"name":"Actively_Exploited_Kev | Oct 27, 2026","url":"https://otx.alienvault.com/pulse/6adf68b85c3e852f3c111d18","created":"2026-10-26"},{"name":"Actively_Exploited_Kev | Oct 24, 2026","url":"https://otx.alienvault.com/pulse/6adb740e397c3ad4799aa4cd","created":"2026-10-23"},{"name":"Actively_Exploited_Kev | Oct 23, 2026","url":"https://otx.alienvault.com/pulse/6ada236fcfba2dfa730ea482","created":"2026-10-22"},{"name":"Actively_Exploited_Kev | Oct 22, 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-2026-50522","tags":["Patch","Vendor Advisory"]},{"url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-50522","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 attacker exploits 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-2026-43767","url":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-43767","exploited":true,"exploitedSince":"2026-07-22","provenance":"source"},"exploits":[],"exploitSources":{"pocGithub":{"count":5,"skipped":0,"earliest":"2026-07-22","earliestUrl":"https://github.com/HORKimhab/CVE-2026-50522","repos":[{"name":"4minx/CVE-2026-50522","url":"https://github.com/4minx/CVE-2026-50522","stars":44,"created":"2026-07-25"},{"name":"WismanSec/sharepoint-2026-poc","url":"https://github.com/WismanSec/sharepoint-2026-poc","stars":2,"created":"2026-07-26"},{"name":"HORKimhab/CVE-2026-50522","url":"https://github.com/HORKimhab/CVE-2026-50522","stars":0,"created":"2026-07-22"},{"name":"ChPratik/CVE-2026-50522","url":"https://github.com/ChPratik/CVE-2026-50522","stars":0,"created":"2026-07-27"},{"name":"darses/CVE-2026-50522","url":"https://github.com/darses/CVE-2026-50522","stars":0,"created":"2026-07-28"}]},"first":{"date":"2026-07-22","source":"PoC-in-GitHub","url":"https://github.com/HORKimhab/CVE-2026-50522"},"provenance":"source"},"exploitRefs":[],"flow":[{"stage":"exploitation","techniques":["T1190"],"provenance":"ai"},{"stage":"primary","techniques":["T1059"],"provenance":"ai"}],"timeline":[{"date":"2026-07-14","kind":"published","label":"Published (NVD)","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-50522","provenance":"source"},{"date":"2026-07-20","kind":"exploited-reported","label":"Exploitation first reported (VulnCheck KEV evidence)","url":"https://x.com/DefusedCyber/status/2079128402855116858","provenance":"source"},{"date":"2026-07-22","kind":"exploit-public","label":"First public exploit: PoC-in-GitHub","url":"https://github.com/HORKimhab/CVE-2026-50522","provenance":"source"},{"date":"2026-07-22","kind":"kev","label":"Added to CISA KEV","url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","provenance":"source"},{"date":"2026-07-22","kind":"euvd-exploited","label":"ENISA EUVD: exploited","url":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-43767","provenance":"source"}],"speed":{"daysToPublicExploit":8,"firstExploitFrom":"PoC-in-GitHub","daysToKev":8},"priority":{"score":72.4,"factors":[{"name":"In a KEV catalog","points":35.0,"detail":"listed in CISA KEV and VulnCheck KEV"},{"name":"Recent KEV 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