How severe is CVE-2026-35439?

CVE-2026-35439 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-2026-35439 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (79th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-35439?

CVE-2026-35439 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-2026-35439?

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-2026-35439 have an EU (EUVD) identifier?

Yes. CVE-2026-35439 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-29637.

When was CVE-2026-35439 published?

CVE-2026-35439 was published on 2026-05-12 and last updated on 2026-06-17.

CVE-2026-35439

CVE-2026-35439 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-502.

Key facts

Severity: High (CVSS 3.x base score 8.8)
EPSS exploit prediction: 2% (79th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-29637
Weakness: CWE-502
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-2026-35439?: Deserialization of untrusted data in Microsoft Office SharePoint allows an authorized attacker to execute code over a network.
How severe is CVE-2026-35439?: CVE-2026-35439 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-2026-35439 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (79th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-35439?: CVE-2026-35439 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-2026-35439?: 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-2026-35439 have an EU (EUVD) identifier?: Yes. CVE-2026-35439 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-29637.
When was CVE-2026-35439 published?: CVE-2026-35439 was published on 2026-05-12 and last updated on 2026-06-17.

References

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

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-502 (Deserialization of Untrusted Data) vulnerabilities

CVE-2026-41104 — Critical (CVSS 10.0): Deserialization of untrusted data in Microsoft Planetary Computer Pro allows an unauthorized attacker to disclose…
CVE-2026-43633 — Critical (CVSS 10.0): HestiaCP versions 1.9.0 through 1.9.4 contain a deserialization vulnerability in the web terminal component caused by a…
CVE-2026-33819 — Critical (CVSS 10.0): Deserialization of untrusted data in Microsoft Bing allows an unauthorized attacker to execute code over a network.
CVE-2026-20131 — Critical (CVSS 10.0): A vulnerability in the web-based management interface of Cisco Secure Firewall Management Center (FMC) Software could…
CVE-2026-25632 — Critical (CVSS 10.0): EPyT-Flow is a Python package designed for the easy generation of hydraulic and water quality scenario data of water…
CVE-2025-14931 — Critical (CVSS 10.0): Hugging Face smolagents Remote Python Executor Deserialization of Untrusted Data Remote Code Execution Vulnerability.…

Browse all CWE-502 (Deserialization of Untrusted Data) vulnerabilities →