Is CVE-2026-35439 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-35439 being exploited in the wild.

How severe is CVE-2026-35439?

High severity, with a CVSS score of 8.8, published 12 May 2026.

Which products and versions are affected?

Microsoft SharePoint Server Subscription Edition up to (excluding) 16.0.19725.20280.

Is there a fix for CVE-2026-35439?

No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

How is CVE-2026-35439 attacked?

It is attacked over the network, in a network appliance.

Am I affected by CVE-2026-35439?

Check whether you run Microsoft SharePoint Server 2016 Enterprise Edition, Microsoft SharePoint Server 2019 or Microsoft SharePoint Server Subscription Edition at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-35439: Microsoft SharePoint insecure deserialization remote code execution

CVE-2026-35439 · Severity: high · CVSS 8.8 · Published 2026-05-12

Microsoft SharePoint, a widely used collaboration and document management platform, contains a security flaw that could allow an authorized user to run malicious code on the server. By exploiting this vulnerability, an attacker with basic user permissions could potentially gain full control over the SharePoint environment, leading to the theft of sensitive corporate data or disruption of business operations. Organizations should apply the latest security updates from Microsoft to protect their internal networks.

Technologies: Microsoft SharePoint Server 2016 Enterprise Edition, Microsoft SharePoint Server 2019, Microsoft SharePoint Server Subscription Edition. Vendors: Microsoft.

Quick answers

Is CVE-2026-35439 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-35439 being exploited in the wild.
How severe is CVE-2026-35439?: High severity, with a CVSS score of 8.8, published 12 May 2026.
Which products and versions are affected?: Microsoft SharePoint Server Subscription Edition up to (excluding) 16.0.19725.20280.
Is there a fix for CVE-2026-35439?: No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2026-35439 attacked?: It is attacked over the network, in a network appliance.
Am I affected by CVE-2026-35439?: Check whether you run Microsoft SharePoint Server 2016 Enterprise Edition, Microsoft SharePoint Server 2019 or Microsoft SharePoint Server Subscription Edition at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

A deserialization vulnerability (CWE-502) exists in Microsoft SharePoint Server due to improper handling of untrusted data. An attacker with Site Member permissions or higher can exploit this by sending a specially crafted network request to a vulnerable SharePoint instance. Successful exploitation allows for remote code execution (RCE) in the context of the SharePoint service account. The vulnerability affects SharePoint Server 2016, 2019, and Subscription Edition; Microsoft has released security updates to address this issue.

Affected products

Microsoft SharePoint Server 2019
Microsoft SharePoint Server 2016 Enterprise Edition
Microsoft SharePoint Server Subscription Edition up to (excluding) 16.0.19725.20280

Timeline

2026-05-12: disclosed: Initial disclosure by Microsoft
2026-05-12: advisory: MSRC advisory published
2026-05-13: other: NVD analysis and CPE mapping updated

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-35439

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