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CVE-2026-40365

Microsoft SharePoint Server insecure deserialization

8.8 HIGHEPSS 1.05%
  1. Published12 May 2026

Description

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

CVSS 3.1 breakdown

Attack vectorNetwork
Attack complexityLow
Privileges requiredLow
User interactionNone
ScopeUnchanged
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected products

Microsoft SharePoint Server2016 · 2019 · < 16.0.19725.20280

Remediation

Fixed in
Microsoft SharePoint Server≥ 16.0.19725.20280

References

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Frequently asked

Is CVE-2026-40365 being actively exploited?

CVE-2026-40365 is not in the CISA KEV catalog. Its EPSS exploit probability is 1.05%.

How severe is CVE-2026-40365?

CVE-2026-40365 has a CVSS 3.1 base score of 8.8, rated high. EPSS estimates a 1.05% probability of exploitation.

Which products are affected by CVE-2026-40365?

Affected products include Microsoft SharePoint Server.

How do I fix CVE-2026-40365?

Upgrade affected software to a fixed version, for example Microsoft SharePoint Server 16.0.19725.20280 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2026-40365 against the real software inventory on every managed device, every day. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

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Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.