CVE-2026-63520

Published Aug 11, 2026

Last updated 2 months ago

Microsoft Office SharePoint

Overview

AI description

Automated description summarized from trusted sources.

CVE-2026-63520 is a remote code execution (RCE) vulnerability affecting Microsoft SharePoint Server. This flaw stems from improper input validation, specifically an unsafe .NET type instantiation issue within SharePoint's Business Connectivity Services or its Federation Service. An attacker can exploit this vulnerability by crafting a malicious input or .NET gadget chain, enabling them to execute arbitrary code on the vulnerable server with the privileges of the SharePoint Site's service account. This vulnerability is frequently highlighted as the second part of a critical exploit chain when combined with CVE-2026-55040, an authentication bypass vulnerability. When chained together, these two vulnerabilities allow for unauthenticated remote code execution against a susceptible SharePoint server. Affected versions include SharePoint Server Subscription Edition, SharePoint Server 2019, and SharePoint Server 2016.

Description: Improper input validation 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: 8.1
Impact score: 5.9
Exploitability score: 2.2
Vector string: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Severity: HIGH

Weaknesses

secure@microsoft.com: CWE-20

Hype score: Not currently trending

Configurations

[
  {
    "nodes": [
      {
        "cpeMatch": [
          {
            "criteria": "cpe:2.3:a:microsoft:sharepoint_server:*:*:*:*:subscription:*:*:*",
            "matchCriteriaId": "D918B8DF-51D1-46F3-8B3F-E4370083BEF6",
            "versionEndExcluding": "16.0.19725.20522",
            "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.