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 (CVE-2026-55040) in Microsoft SharePoint Enterprise Server 2016 is classified under CWE-1390 (Weak Authentication). It allows an attacker without privileges to bypass authentication mechanisms remotely over a network, potentially leading to unauthorized access. The CVSS v3.1 base score is 9.1, reflecting network attack vector, low attack complexity, no privileges required, no user interaction, and high impact on confidentiality and integrity. Microsoft has published an official fix for this vulnerability, as detailed in their security advisory.
Potential Impact
Successful exploitation of this vulnerability could allow an attacker to bypass authentication controls, leading to unauthorized access to sensitive information and compromising the confidentiality and integrity of the affected SharePoint server. Availability is not impacted. There are no known exploits in the wild at this time.
Mitigation Recommendations
An official fix is available from Microsoft for this vulnerability. Users of Microsoft SharePoint Enterprise Server 2016 version 16.0.0 should apply the security update provided in the Microsoft advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-55040 to remediate this issue.
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 (CVE-2026-55040) in Microsoft SharePoint Enterprise Server 2016 is classified under CWE-1390 (Weak Authentication). It allows an attacker without privileges to bypass authentication mechanisms remotely over a network, potentially leading to unauthorized access. The CVSS v3.1 base score is 9.1, reflecting network attack vector, low attack complexity, no privileges required, no user interaction, and high impact on confidentiality and integrity. Microsoft has published an official fix for this vulnerability, as detailed in their security advisory.
Potential Impact
Successful exploitation of this vulnerability could allow an attacker to bypass authentication controls, leading to unauthorized access to sensitive information and compromising the confidentiality and integrity of the affected SharePoint server. Availability is not impacted. There are no known exploits in the wild at this time.
Mitigation Recommendations
An official fix is available from Microsoft for this vulnerability. Users of Microsoft SharePoint Enterprise Server 2016 version 16.0.0 should apply the security update provided in the Microsoft advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-55040 to remediate this issue.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- microsoft
- Date Reserved
- 2026-06-16T14:13:49.835Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- official-fix
- Vendor Advisory Urls
- [{"url":"https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-55040","vendor":"Microsoft"}]
Threat ID: 6a5676b168715ace43f09931
Added to database: 07/14/2026, 17:49:37 UTC
Last enriched: 08/13/2026, 18:10:31 UTC
Last updated: 08/29/2026, 04:07:57 UTC
Views: 152
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