CVE-2026-58644

Published Jul 14, 2026

Last updated a month ago

Exploit known CVSS critical 9.8

Microsoft Office

Cloud

Zero-day

ICS

Server

Port (443)

SharePoint

Overview

AI description

Automated description summarized from trusted sources.

CVE-2026-58644 is a vulnerability found in Microsoft Office SharePoint, categorized as a deserialization of untrusted data flaw. This vulnerability enables an unauthorized attacker to execute code over a network. The flaw affects multiple versions of Microsoft SharePoint Server, including Subscription Edition, 2019, and 2016. The Cybersecurity and Infrastructure Security Agency (CISA) has added CVE-2026-58644 to its Known Exploited Vulnerabilities Catalog, indicating that it is being actively exploited.

Description: Deserialization of untrusted data in Microsoft Office SharePoint allows an unauthorized attacker to execute code over a network.
Source: secure@microsoft.com
NVD status: Analyzed
Products: sharepoint_server

Risk scores

CVSS 3.1

Type: Secondary
Base score: 9.8
Impact score: 5.9
Exploitability score: 3.9
Vector string: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Severity: CRITICAL

Known exploits

Data from CISA

Vulnerability name: Microsoft SharePoint Deserialization of Untrusted Data Vulnerability
Exploit added on: Jul 16, 2026
Exploit action due: Jul 19, 2026
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.

Weaknesses

secure@microsoft.com: CWE-502

Hype score: Not currently trending

Configurations

[
  {
    "nodes": [
      {
        "cpeMatch": [
          {
            "criteria": "cpe:2.3:a:microsoft:sharepoint_server:*:*:*:*:subscription:*:*:*",
            "matchCriteriaId": "5FA63EA8-B225-4E35-A6A3-DBDECF5AC4C8",
            "versionEndExcluding": "16.0.19725.20434",
            "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"
      }
    ]
  }
]

References

Sources include official advisories and independent security research.