How to fix CVE-2025-21393?

Within 30 days: Identify affected systems and apply vendor patches as part of regular patch cycle. Verify Content-Security-Policy and output encoding.

Is Sharepoint Server affected by CVE-2025-21393?

CVE-2025-21393 presents moderate security risk, a cross-site scripting vulnerability rated CVSS 6.3. Attackers could inject scripts to steal sessions or perform actions as authenticated users. A patch is available and should be applied during regular vulnerability management.

CVE-2025-21393

MEDIUM

2025-01-14 [email protected]

6.3

CVSS 3.1

CVSS Vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:L/A:N

Attack Vector

Network

Attack Complexity

Low

Privileges Required

Low

User Interaction

Required

Scope

Unchanged

Confidentiality

High

Integrity

Low

Availability

None

Lifecycle Timeline

Analysis Generated

Mar 28, 2026 - 18:03 vuln.today

Patch Released

Mar 28, 2026 - 18:03 nvd

Patch available

CVE Published

Jan 14, 2025 - 18:16 nvd

MEDIUM 6.3

Description

Microsoft SharePoint Server Spoofing Vulnerability

Analysis

Microsoft SharePoint Server Spoofing Vulnerability. Rated medium severity (CVSS 6.3), this vulnerability is remotely exploitable, low attack complexity. This Cross-Site Scripting (XSS) vulnerability could allow attackers to inject malicious scripts into web pages viewed by other users.

Technical Context

This vulnerability is classified as Cross-Site Scripting (XSS) (CWE-79), which allows attackers to inject malicious scripts into web pages viewed by other users. Affected products include: Microsoft Sharepoint Server.

Affected Products

Microsoft Sharepoint Server.

Remediation

A vendor patch is available. Apply the latest security update as soon as possible. Sanitize all user input, use Content-Security-Policy headers, encode output contextually (HTML, JS, URL). Use frameworks with built-in XSS protection.

Priority Score

Low Medium High Critical

KEV: 0

EPSS: +0.2

CVSS: +32

POC: 0

CVE-2025-21393 vulnerability details – vuln.today

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