# CVE-2026-58644 — Microsoft SharePoint Enterprise Server 2016 > As of 2026-07-15, CVE-2026-58644 is a CRITICAL-severity vulnerability in Microsoft SharePoint Enterprise Server 2016, CVSS v3.1 9.8, EPSS 1.3% (67.6th percentile). Threadlinqs Intelligence links 13 tracked threat campaigns to CVE-2026-58644, most recently “CISA Adds Exploited SharePoint RCE Zero-Day CVE-2026-58644 to KEV Catalog”. **Last updated:** 2026-07-15 ## What is CVE-2026-58644? Deserialization of untrusted data in Microsoft Office SharePoint allows an unauthorized attacker to execute code over a network. The record classifies CVE-2026-58644 under weakness class [CWE-502](https://cwe.mitre.org/data/definitions/502.html). Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs no prior authentication, needs no user interaction, and has high impact on confidentiality, integrity, availability. 3 affected-product entries are recorded, across 1 vendor, listed below. The identifier was first published 60 days ago. ## Severity and exploitation probability - **CVSS v3.1 base score:** 9.8 — CRITICAL (`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`) - **EPSS (FIRST):** 1.3% probability of exploitation in the next 30 days, higher than 67.6% of all scored CVEs - **CISA KEV:** Not listed in the CISA Known Exploited Vulnerabilities catalog - **Threadlinqs priority:** 7.6/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability - **Published:** 2026-07-14, last modified 2026-07-15 ## Is CVE-2026-58644 being exploited? No public exploitation evidence for CVE-2026-58644 is recorded in the sources Threadlinqs tracks — CISA KEV, Exploit-DB, public proof-of-concept repositories and ProjectDiscovery Nuclei — as of 2026-07-15. That is an absence of evidence in those feeds, not a guarantee that the vulnerability is unexploited. ## Affected products and versions - **Microsoft**: SharePoint Enterprise Server 2016, SharePoint Server 2019, SharePoint Server Subscription Edition ## How to fix CVE-2026-58644 The record marks a vendor fix as available for CVE-2026-58644. Patch reference: [https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-58644](https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-58644). Vendor advisory: [https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-58644](https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-58644). Apply the vendor fix referenced above to every affected product listed in this record, then confirm the running version against the vendor advisory. ## Threat activity tracking CVE-2026-58644 13 tracked threats in the Threadlinqs corpus reference CVE-2026-58644, either in the campaign’s CVE list or as an indicator on the campaign record. - [CISA Adds Exploited SharePoint RCE Zero-Day CVE-2026-58644 to KEV Catalog](https://intel.threadlinqs.com/threat/TL-2026-1434) — CRITICAL · 2026-07-17 - [July 2026 Patch Tuesday: Actively Exploited SharePoint RCE (CVE-2026-58644) and AD FS/SharePoint Zero-Days](https://intel.threadlinqs.com/threat/TL-2026-1437) — CRITICAL · 2026-07-17 - [CVE-2026-58644: Microsoft SharePoint Server Unauthenticated Remote Code Execution Exploited in the Wild](https://intel.threadlinqs.com/threat/TL-2026-1460) — CRITICAL · 2026-07-17 - [Microsoft July 2026 Patch Tuesday: Two Actively Exploited Zero-Days in AD FS (CVE-2026-56155) and SharePoint (CVE-2026-56164), Plus Unpatched BitLocker Bypass (CVE-2026-50661)](https://intel.threadlinqs.com/threat/TL-2026-1350) — CRITICAL · 2026-07-15 - [Actively Exploited SharePoint Server Elevation of Privilege Flaw (CVE-2026-56164) Patched Alongside Critical RCE Pair in July 2026 Patch Tuesday](https://intel.threadlinqs.com/threat/TL-2026-1364) — CRITICAL · 2026-07-15 - [July 2026 Patch Tuesday: Microsoft Fixes 622 CVEs Including Three Actively-Targeted Zero-Days (CVE-2026-56155 AD FS EoP, CVE-2026-56164 SharePoint EoP, CVE-2026-50661 BitLocker Bypass)](https://intel.threadlinqs.com/threat/TL-2026-1372) — CRITICAL · 2026-07-15 - [CISA Warns of Trio of Actively Exploited SharePoint Server Flaws (CVE-2026-32201, CVE-2026-45659, CVE-2026-56164)](https://intel.threadlinqs.com/threat/TL-2026-1378) — CRITICAL · 2026-07-15 - [Microsoft July 2026 Patch Tuesday: 570 Flaws Fixed, 3 Zero-Days Including AD FS and SharePoint Privilege Escalation](https://intel.threadlinqs.com/threat/TL-2026-1324) — CRITICAL · 2026-07-14 - [Microsoft July 2026 Patch Tuesday: 570 Vulnerabilities Fixed, Including 2 Actively Exploited Zero-Days (CVE-2026-56164, CVE-2026-56155)](https://intel.threadlinqs.com/threat/TL-2026-1325) — CRITICAL · 2026-07-14 - [Microsoft July 2026 Patch Tuesday: 569 CVEs, Two Actively Exploited Zero-Days (CVE-2026-56155 AD FS EoP, CVE-2026-56164 SharePoint EoP)](https://intel.threadlinqs.com/threat/TL-2026-1327) — CRITICAL · 2026-07-14 - [Microsoft July 2026 Patch Tuesday: Record 622 CVEs Include Two Actively Exploited Zero-Days in AD FS (CVE-2026-56155) and SharePoint Server (CVE-2026-56164)](https://intel.threadlinqs.com/threat/TL-2026-1331) — CRITICAL · 2026-07-14 - [Microsoft July 2026 Patch Tuesday: Record 622 Flaws Fixed, Two Zero-Days Under Active Exploitation (CVE-2026-56164, CVE-2026-56155)](https://intel.threadlinqs.com/threat/TL-2026-1334) — CRITICAL · 2026-07-14 - [Microsoft July 2026 Patch Tuesday: Two Actively Exploited Zero-Days in AD FS and SharePoint (CVE-2026-56155, CVE-2026-56164)](https://intel.threadlinqs.com/threat/TL-2026-1336) — CRITICAL · 2026-07-14 ## Sources Enriched from CVE.org, NVD, FIRST EPSS, GitHub Security Advisories. Last verified by Threadlinqs on 2026-07-16. This product uses the NVD API but is not endorsed or certified by the NVD. **Vendor advisory and patch** - [msrc.microsoft.com — vendor advisory](https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-58644) Canonical: https://intel.threadlinqs.com/cve/CVE-2026-58644 Full detection coverage and IOCs for threats exploiting CVE-2026-58644 via the Threadlinqs MCP server (Purple tier): https://intel.threadlinqs.com/mcp