CVE-2026-63520

High8.1Published on August 11, 2026

Improper input validation in Microsoft Office SharePoint allows an unauthorized attacker to execute code over a network.

Early warning: exploitation observed

Exploitation observed since Aug 25, 2026
Not yet in the official CISA catalogue
First attack observed 13 days after disclosure

Source: VulnCheck KEV · Aug 26, 2026 Aug 25, 2026

CVSS score8.1 / 10CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Weakness type (CWE)CWE-20

Vendorsmicrosoft

Affected products

Vendors	Product	Versions
microsoft	sharepoint server	< 16.0.19725.20522

Vulnerabilities

SharePoint Exploit Chain Enables Unauthenticated RCE

Critical SharePoint vulnerabilities CVE-2026-55040 and CVE-2026-63520 allow unauthenticated remote code execution via an exploit chain, affecting SharePoint Server 2019, 2016, and Subscription Edition.

Aug 12, 202607:093 min readRead

This product uses the NVD API but is not endorsed or certified by the NVD.

CVE database

Early warning: exploitation observed

Affected products

Related articles

SharePoint Exploit Chain Enables Unauthenticated RCE