CVE-2026-55040: CWE-1390: Weak Authentication in Microsoft Microsoft SharePoint Enterprise Server 2016
Weak authentication in Microsoft Office SharePoint allows an unauthorized attacker to bypass a security feature over a network.
AI Analysis
Technical Summary
This vulnerability, identified as CWE-1390 (Weak Authentication), affects Microsoft SharePoint Enterprise Server 2016 (version 16.0.0). It enables an attacker with no privileges and no user interaction to bypass authentication mechanisms remotely over a network. The CVSS v3.1 base score is 9.1, reflecting critical severity with high impact on confidentiality and integrity but no impact on availability. The vendor has released an official fix to address this issue.
Potential Impact
Successful exploitation allows an attacker to bypass authentication controls, resulting in full compromise of confidentiality and integrity of the affected SharePoint server. This can lead to unauthorized access to sensitive information and potential manipulation of data. There is no known exploitation in the wild at this time.
Mitigation Recommendations
An official fix is available from Microsoft for this vulnerability. It is recommended to apply the provided patch promptly to remediate the issue. Since this is not a cloud service, remediation depends on applying the vendor's update to the affected on-premises SharePoint server.
CVE-2026-55040: CWE-1390: Weak Authentication in Microsoft Microsoft SharePoint Enterprise Server 2016
Description
Weak authentication in Microsoft Office SharePoint allows an unauthorized attacker to bypass a security feature over a network.
CVSS v3.1
Score 9.1critical
Affected software
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
This vulnerability, identified as CWE-1390 (Weak Authentication), affects Microsoft SharePoint Enterprise Server 2016 (version 16.0.0). It enables an attacker with no privileges and no user interaction to bypass authentication mechanisms remotely over a network. The CVSS v3.1 base score is 9.1, reflecting critical severity with high impact on confidentiality and integrity but no impact on availability. The vendor has released an official fix to address this issue.
Potential Impact
Successful exploitation allows an attacker to bypass authentication controls, resulting in full compromise of confidentiality and integrity of the affected SharePoint server. This can lead to unauthorized access to sensitive information and potential manipulation of data. There is no known exploitation in the wild at this time.
Mitigation Recommendations
An official fix is available from Microsoft for this vulnerability. It is recommended to apply the provided patch promptly to remediate the issue. Since this is not a cloud service, remediation depends on applying the vendor's update to the affected on-premises SharePoint server.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- GHSA-grxw-7cvc-96rv
- Osv Schema Version
- 1.4.0
- Aliases
- ["CVE-2026-55040"]
- Database Specific Severity
- CRITICAL
- Cvss Version
- 3.1
- Remediation Level
- official-fix
- State
- PUBLISHED
Threat ID: 6a7e0369bf8831d5398f8970
Added to database: 08/13/2026, 17:48:25 UTC
Last enriched: 09/12/2026, 04:31:26 UTC
Last updated: 09/27/2026, 01:47:43 UTC
Views: 40
Community Reviews
0 reviewsCrowdsource mitigation strategies, share intel context, and vote on the most helpful responses. Sign in to add your voice and help keep defenders ahead.
Want to contribute mitigation steps or threat intel context? Sign in or create an account to join the community discussion.
Actions
Updates to AI analysis require Pro Console access. Upgrade inside Console → Billing.
Need more coverage?
Upgrade to Pro Console for AI refresh and higher limits.
For incident response and remediation, OffSeq services can help resolve threats faster.
Latest Threats
Check if your credentials are on the dark web
Instant breach scanning across billions of leaked records. Free tier available.