CVE-2025-53771: Microsoft SharePoint Server Auth Bypass

CVE-2025-53771 Overview

Improper authentication in Microsoft Office SharePoint allows an unauthorized attacker to perform spoofing over a network.

Critical Impact

This vulnerability may allow attackers to impersonate legitimate users, leading to potential data breaches and unauthorized access.

Affected Products

• Microsoft SharePoint Server Subscription
• Microsoft SharePoint Server 2016
• Microsoft SharePoint Server 2019

Discovery Timeline

• 2025-07-20 - CVE CVE-2025-53771 published to NVD
• 2025-08-14 - Last updated in NVD database

Technical Details for CVE-2025-53771

Vulnerability Analysis

CVE-2025-53771 stems from improper authentication handling within Microsoft Office SharePoint. The absence of robust authentication mechanisms allows an attacker possessing network access to spoof identities and interact with systems at an elevated privilege level.

Root Cause

The root cause is a flawed authentication protocol within SharePoint's network communications, where essential identity verification steps are bypassed or inadequately enforced.

Attack Vector

This vulnerability can be exploited over a network, allowing remote attackers to impersonate users by intercepting or crafting specific network requests.

# Example exploitation code (sanitized)
import requests

def spoof_user(session_url, headers):
    try:
        response = requests.post(session_url, headers=headers)
        if response.status_code == 200:
            print("Spoofing Successful")
        else:
            print("Spoofing Failed")
    except Exception as e:
        print(f"Error during exploitation: {e}")

Detection Methods for CVE-2025-53771

Indicators of Compromise

• Unexpected user sessions initiated
• Anomalous network traffic from unrecognized IP addresses
• Discrepancies in user session logs

Detection Strategies

Implement regular log auditing and anomaly detection systems to identify unusual login patterns or session authentications originating from unusual network locations.

Monitoring Recommendations

Use network monitoring tools to watch for abnormal login attempts or spoofed session initiations. Ensure alerts are triggered for authentication attempts outside normal parameters.

How to Mitigate CVE-2025-53771

Immediate Actions Required

• Enable multi-factor authentication (MFA) for all SharePoint users
• Conduct a review of all current user access logs
• Isolate any detected anomalies as potential breach attempts

Patch Information

Monitor Microsoft's advisory page for the release of a comprehensive security patch: Microsoft Advisory.

Workarounds

Implement strict network segmentation to limit potential attack vectors and reduce exposure of network resources.

# Configuration example to enhance security
networkSegmentation {
    externalAccess: false;
    subnetAccess {
        trustedSubnets: ["192.168.1.0/24", "192.168.2.0/24"];
    }
}