Microsoft SharePoint Enterprise Server prior 16.0.5552.1002 insufficient granularity of access control

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
8.1$0-$5k0.00

Summaryinfo

A vulnerability was found in Microsoft SharePoint Enterprise Server, SharePoint Foundation and Project Server. It has been classified as critical. This vulnerability affects unknown code. The manipulation leads to insufficient granularity of access control. This vulnerability is traded as CVE-2026-40365. It is possible to initiate the attack remotely. There is no exploit available. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability, which was classified as critical, has been found in Microsoft SharePoint Enterprise Server, SharePoint Foundation and Project Server. This issue affects an unknown code block. The manipulation with an unknown input leads to a insufficient granularity of access control vulnerability. Using CWE to declare the problem leads to CWE-1220. The product implements access controls via a policy or other feature with the intention to disable or restrict accesses (reads and/or writes) to assets in a system from untrusted agents. However, implemented access controls lack required granularity, which renders the control policy too broad because it allows accesses from unauthorized agents to the security-sensitive assets. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

Deserialization of untrusted data in Microsoft Office SharePoint allows an authorized attacker to execute code over a network.

The weakness was shared 05/12/2026 as confirmed security update guide (Website). It is possible to read the advisory at msrc.microsoft.com. The identification of this vulnerability is CVE-2026-40365. The exploitation is known to be easy. The attack may be initiated remotely. The technical details are unknown and an exploit is not publicly available. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 06/04/2026).

The vulnerability scanner Nessus provides a plugin with the ID 314345 (Security Updates for Microsoft SharePoint Server 2019 (May 2026)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 16.0.5552.1002 eliminates this vulnerability. A possible mitigation has been published immediately after the disclosure of the vulnerability.

The vulnerability is also documented in the vulnerability database at Tenable (314345). Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Productinfo

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Vendor

Name

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 8.8
VulDB Meta Temp Score: 8.1

VulDB Base Score: 8.8
VulDB Temp Score: 7.7
VulDB Vector: 🔒
VulDB Reliability: 🔍

Vendor Base Score (Microsoft): 8.8
Vendor Vector (Microsoft): 🔒

CNA Base Score: 8.8
CNA Vector (Microsoft): 🔒

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Insufficient granularity of access control
CWE: CWE-1220 / CWE-284 / CWE-266
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Unproven

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 314345
Nessus Name: Security Updates for Microsoft SharePoint Server 2019 (May 2026)

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

Reaction Time: 🔒
0-Day Time: 🔒
Exposure Time: 🔒

Upgrade: SharePoint Enterprise Server/SharePoint Foundation/Project Server 16.0.5552.1002

Timelineinfo

05/12/2026 VulDB entry created
05/12/2026 +0 days Advisory disclosed
05/12/2026 +0 days Countermeasure disclosed
06/04/2026 +23 days VulDB entry last update

Sourcesinfo

Vendor: microsoft.com

Advisory: msrc.microsoft.com
Status: Confirmed

CVE: CVE-2026-40365 (🔒)
GCVE (CVE): GCVE-0-2026-40365
GCVE (VulDB): GCVE-100-363179

Entryinfo

Created: 05/12/2026 19:38
Updated: 06/04/2026 18:27
Changes: 05/12/2026 19:38 (36), 05/12/2026 19:42 (33), 05/13/2026 12:36 (2), 06/04/2026 18:27 (11)
Complete: 🔍
Cache ID: 216::103

Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

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