Microsoft SharePoint Server Security Feature Bypass Vulnerability

Source data

Overview

Weak authentication in Microsoft Office SharePoint allows an unauthorized attacker to bypass a security feature over a network.

Impact & technical details

Security Feature Bypass

What kind of security feature could be bypassed by successfully exploiting this vulnerability? The authentication feature could be bypassed as this vulnerability allows impersonation.

I am running SharePoint Server 2016. Do the updates for SharePoint Enterprise Server 2016 also apply to the version I am running? Yes. The same KB number applies to both SharePoint Server 2016 and SharePoint Enterprise Server 2016. Customers running either version should install the security update to be protected from this vulnerability.

According to the CVSS metrics, successful exploitation of this vulnerability could lead to major loss of confidentiality (C:H), and integrity (I:H), but could lead to no loss of availability (A:N). What does that mean for this vulnerability? Exploiting this vulnerability could allow an attacker to disclose files and modify data, but the attacker cannot impact the availability of the system.

How could an attacker exploit this vulnerability? In a network-based attack, an unauthenticated attacker could bypass authentication and make an anonymous connection.

CVSS base score

9.1 / 10

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N/E:U/RL:O/RC:C

Highest base score supplied by MSRC for this record; the vector belongs to that score. Ratings can vary by product. Microsoft Important is displayed as High; Moderate is displayed as Medium.

Affected products

• Microsoft SharePoint Enterprise Server 2016
• Microsoft SharePoint Server 2019
• Microsoft SharePoint Server Subscription Edition

Source guidance

Remediation

• 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.

At least one Microsoft vendor-fix reference is available. Check each affected product for its applicable update, prerequisites, and supported version.

Authoritative sources & updates

Findings and update information come from the linked publishers. GTP compiles the public record and provides the recommendation above. CVSS ratings shown here come from Microsoft. NVD references provide additional public context.

• Microsoft Security Response Center (opens in a new tab)
• Microsoft security update · 5002891 (opens in a new tab)
• Microsoft remediation guidance (opens in a new tab)
• Microsoft security update · 5002883 (opens in a new tab)
• Microsoft remediation guidance (opens in a new tab)
• Microsoft security update · 5002882 (opens in a new tab)
• Microsoft remediation guidance (opens in a new tab)
• CISA Known Exploited Vulnerabilities (opens in a new tab)
• Authoritative advisory (opens in a new tab)
• Authoritative advisory (opens in a new tab)
• NIST National Vulnerability Database (opens in a new tab)