{"cve":{"cve_id":"CVE-2026-58644","is_kev":true,"kev_date_added":"2026-07-16","kev_vendor_project":"Microsoft","kev_product":"SharePoint","kev_vulnerability_name":"Microsoft SharePoint Deserialization of Untrusted Data Vulnerability","kev_short_description":"Microsoft SharePoint contains a deserialization of untrusted data vulnerability that allows an unauthorized attacker to execute code over a network.","kev_required_action":"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.","kev_due_date":"2026-07-19","kev_known_ransomware":false,"kev_notes":"https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-58644 ; 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-2026-58644","kev_cwes":["CWE-502"],"epss_score":0.15873,"epss_percentile":0.96634,"epss_as_of":"2026-08-26","description":"Deserialization of untrusted data in Microsoft Office SharePoint allows an unauthorized attacker to execute code over a network.","published_at":"2026-07-14T17:05:37.431000Z","last_modified_at":"2026-07-17T05:16:40.470000Z","cvss_v3_score":9.8,"cvss_v3_vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:F/RL:O/RC:C","cvss_v3_severity":"CRITICAL","cvss_v4_score":null,"cvss_v4_vector":null,"cvss_v4_severity":null,"ssvc_decision":null,"ssvc_exploitation":"active","ssvc_automatable":true,"ssvc_technical_impact":"total","cwes":["CWE-502"],"nvd_references":["https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-58644"],"vuln_status":"Analyzed","trending_score":null,"is_trending":false,"has_trended":false,"trended_number_one":false,"trending_peak_score":null,"trending_peak_rank":null,"started_trending_at":null,"trended_number_one_at":null,"summary_generated":null,"summary_generated_at":null,"summary_model":null,"created_at":"2026-07-14T18:33:20.779180Z","updated_at":"2026-07-18T02:35:04.258404Z"},"effective_severity":"CRITICAL","badges":["kev","poc","news"],"impact_analysis":[],"cvss_v3_decoded":{"version":"3.1","metrics":[{"metric":"AV","name":"Attack Vector","value":"N","value_label":"Network"},{"metric":"AC","name":"Attack Complexity","value":"L","value_label":"Low"},{"metric":"PR","name":"Privileges Required","value":"N","value_label":"None"},{"metric":"UI","name":"User Interaction","value":"N","value_label":"None"},{"metric":"S","name":"Scope","value":"U","value_label":"Unchanged"},{"metric":"C","name":"Confidentiality","value":"H","value_label":"High"},{"metric":"I","name":"Integrity","value":"H","value_label":"High"},{"metric":"A","name":"Availability","value":"H","value_label":"High"},{"metric":"E","name":"E","value":"F","value_label":"F"},{"metric":"RL","name":"RL","value":"O","value_label":"O"},{"metric":"RC","name":"RC","value":"C","value_label":"Changed"}]},"cvss_v4_decoded":{"version":null,"metrics":[]},"affected":[{"vendor_slug":"microsoft","vendor_name":"microsoft","product_slug":"microsoft-sharepoint-enterprise-server-2016","product_name":"Microsoft SharePoint Enterprise Server 2016","version_start":"16.0.0","version_start_inclusive":true,"version_end":"16.0.5556.1005","version_end_inclusive":false,"cpe23_uri":"cve5:microsoft:microsoft-sharepoint-enterprise-server-2016:16.0.0:16.0.5556.1005"},{"vendor_slug":"microsoft","vendor_name":"microsoft","product_slug":"microsoft-sharepoint-server-2019","product_name":"Microsoft SharePoint Server 2019","version_start":"16.0.0","version_start_inclusive":true,"version_end":"16.0.10417.20153","version_end_inclusive":false,"cpe23_uri":"cve5:microsoft:microsoft-sharepoint-server-2019:16.0.0:16.0.10417.20153"},{"vendor_slug":"microsoft","vendor_name":"microsoft","product_slug":"microsoft-sharepoint-server-subscription-edition","product_name":"Microsoft SharePoint Server Subscription Edition","version_start":"16.0.0","version_start_inclusive":true,"version_end":"16.0.19725.20384","version_end_inclusive":false,"cpe23_uri":"cve5:microsoft:microsoft-sharepoint-server-subscription-edition:16.0.0:16.0.19725.20384"},{"vendor_slug":"microsoft","vendor_name":"microsoft","product_slug":"sharepoint-server","product_name":"sharepoint_server","version_start":null,"version_start_inclusive":null,"version_end":"16.0.19725.20434","version_end_inclusive":false,"cpe23_uri":"cpe:2.3:a:microsoft:sharepoint_server:*:*:*:*:subscription:*:*:*"},{"vendor_slug":"microsoft","vendor_name":"microsoft","product_slug":"sharepoint-server","product_name":"sharepoint_server","version_start":"2016","version_start_inclusive":true,"version_end":"2016","version_end_inclusive":true,"cpe23_uri":"cpe:2.3:a:microsoft:sharepoint_server:2016:*:*:*:enterprise:*:*:*"},{"vendor_slug":"microsoft","vendor_name":"microsoft","product_slug":"sharepoint-server","product_name":"sharepoint_server","version_start":"2019","version_start_inclusive":true,"version_end":"2019","version_end_inclusive":true,"cpe23_uri":"cpe:2.3:a:microsoft:sharepoint_server:2019:*:*:*:*:*:*:*"}],"exploit_refs":[{"source":"nuclei","kind":"nuclei","url":"https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2026/CVE-2026-58644.yaml","title":"Microsoft SharePoint Server - WS-Federation BinaryFormatter Deserialization RCE","author":"pdteam","disclosed_at":null}],"news":[{"id":652,"source":"The Hacker News","url":"https://thehackernews.com/2026/07/cisa-adds-exploited-sharepoint-rce-zero.html","title":"CISA Adds Exploited SharePoint RCE Zero-Day CVE-2026-58644 to KEV","summary":"The U.S. Cybersecurity and Infrastructure Security Agency (CISA) on Thursday added a newly patched security flaw impacting Microsoft SharePoint Server to its Known Exploited Vulnerabilities (KEV) catalog, requiring Federal Civilian Executive Branch (FCEB) agencies to apply the fixes by July 19, 2026.\n\nThe vulnerability in question is CVE-2026-58644 (CVSS score: 9.8), a critical deserialization","thumbnail_url":"https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgH1X7ZnvKsW37BBvjNfEzT4Imh9ZIRL4_2W1JaNVe_MyO3Q5H1MPsET-SASqznhlfOExRrLj4-6NzhgvGi76w4U5tSmlM-pJLIqO5jF3g9G1DR_FNhuwcatBFb8ARvD4PPMiQvMCFiTlEOlc13nQbQqCn5ZHf1J2ZOqDeG3_pmBiQ92hTfMErJKcjKbNtZ/s1600/sharepoint-cisa.jpg","author":"info@thehackernews.com (The Hacker News)","published_at":"2026-07-17T06:42:23Z","fetched_at":"2026-07-17T07:33:28.919517Z","trending_score":7.560871025771483e-7,"cve_ids":["CVE-2026-58644"]}],"references":[{"url":"https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-58644","source_type":"VENDOR_ADVISORY","tags":["advisory"]}],"timeline":[{"type":"published","at":"2026-07-14T17:05:37.431000Z","label":"CVE published","source":null},{"type":"cvss_changed","at":"2026-07-15T19:33:20.787871Z","label":"CVSS score revised","source":"cvelistv5"},{"type":"cisa_reported","at":"2026-07-16T00:00:00Z","label":"Added to CISA KEV catalog","source":"kev"},{"type":"ssvc_changed","at":"2026-07-16T17:36:28.572765Z","label":"SSVC decision revised","source":"vulnrichment"},{"type":"ssvc_changed","at":"2026-07-16T17:36:28.572765Z","label":"SSVC decision revised","source":"vulnrichment"},{"type":"ssvc_changed","at":"2026-07-16T17:36:28.572765Z","label":"SSVC decision revised","source":"vulnrichment"},{"type":"ssvc_changed","at":"2026-07-16T18:36:28.548916Z","label":"SSVC decision revised","source":"vulnrichment"},{"type":"first_article","at":"2026-07-17T06:42:23Z","label":"First news coverage","source":"The Hacker News"},{"type":"poc_available","at":"2026-08-14T18:36:17.708478Z","label":"Public PoC available","source":"nuclei"}]}