How severe is CVE-2026-40365?

CVE-2026-40365 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2026-40365 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (57th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-40365?

CVE-2026-40365 primarily affects Microsoft Sharepoint Server. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2026-40365?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-40365 have an EU (EUVD) identifier?

Yes. CVE-2026-40365 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-29647.

When was CVE-2026-40365 published?

CVE-2026-40365 was published on 2026-05-12 and last updated on 2026-06-17.

CVE-2026-40365

CVE-2026-40365 is a high-severity vulnerability in Microsoft Sharepoint Server with a CVSS 3.x base score of 8.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-1220.

Key facts

Severity: High (CVSS 3.x base score 8.8)
EPSS exploit prediction: 1% (57th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-29647
Weakness: CWE-1220
Affected product: Microsoft Sharepoint Server
Published: 2026-05-12
Last modified: 2026-06-17

Description

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

Frequently asked questions

What is CVE-2026-40365?: Deserialization of untrusted data in Microsoft Office SharePoint allows an authorized attacker to execute code over a network.
How severe is CVE-2026-40365?: CVE-2026-40365 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2026-40365 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (57th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-40365?: CVE-2026-40365 primarily affects Microsoft Sharepoint Server. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2026-40365?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-40365 have an EU (EUVD) identifier?: Yes. CVE-2026-40365 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-29647.
When was CVE-2026-40365 published?: CVE-2026-40365 was published on 2026-05-12 and last updated on 2026-06-17.

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-40365

Affected products (3)

cpe:2.3:a:microsoft:sharepoint_server:*:*:*:*:subscription:*:*:*
cpe:2.3:a:microsoft:sharepoint_server:2016:*:*:*:enterprise:*:*:*
cpe:2.3:a:microsoft:sharepoint_server:2019:*:*:*:*:*:*:*

More vulnerabilities in Microsoft Sharepoint Server

CVE-2013-1330 — Critical (CVSS 10.0): The default configuration of Microsoft SharePoint Portal Server 2003 SP3, SharePoint Server 2007 SP3 and 2010 SP1 and…
CVE-2020-1595 — Critical (CVSS 9.9): <p>A remote code execution vulnerability exists in Microsoft SharePoint where APIs aren't properly protected from…
CVE-2020-1210 — Critical (CVSS 9.9): <p>A remote code execution vulnerability exists in Microsoft SharePoint when the software fails to check the source…
CVE-2026-20963 — Critical (CVSS 9.8): Deserialization of untrusted data in Microsoft Office SharePoint allows an unauthorized attacker to execute code over a…
CVE-2025-53770 — Critical (CVSS 9.8): Deserialization of untrusted data in on-premises Microsoft SharePoint Server allows an unauthorized attacker to execute…
CVE-2023-29357 — Critical (CVSS 9.8): Microsoft SharePoint Server Elevation of Privilege Vulnerability

All CVEs affecting Microsoft Sharepoint Server →

Other CWE-1220 vulnerabilities

CVE-2025-31201 — Critical (CVSS 9.8): This issue was addressed by removing the vulnerable code. This issue is fixed in iOS 18.4.1 and iPadOS 18.4.1, macOS…
CVE-2022-2475 — Critical (CVSS 9.8): Haas Controller version 100.20.000.1110 has insufficient granularity of access control when using the "Ethernet Q…
CVE-2026-6356 — Critical (CVSS 9.6): A vulnerability in the web application allows standard users to escalate their privileges to those of a super…
CVE-2026-6388 — Critical (CVSS 9.1): A flaw was found in ArgoCD Image Updater. This vulnerability allows an attacker, with permissions to create or modify…
CVE-2025-8053 — Critical (CVSS 9.1): Insufficient Granularity of Access Control vulnerability in opentext Flipper allows Exploiting Incorrectly Configured…
CVE-2025-7493 — Critical (CVSS 9.1): A privilege escalation flaw from host to domain administrator was found in FreeIPA. This vulnerability is similar to…

Browse all CWE-1220 vulnerabilities →