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CVE-2026-40368 is a remote code execution vulnerability in Microsoft Office SharePoint caused by deserialization of untrusted data. SharePoint processes attacker-controlled serialized data without sufficient validation, enabling code execution in a network-accessible attack path. Microsoft characterizes the issue as exploitable by an authenticated attacker with low privileges, with user interaction required. Available vendor context indicates exploitation involves a client connecting to a malicious server, after which the unsafe deserialization condition can lead to code execution on the client. The vulnerability affects supported on-premises SharePoint product lines addressed by Microsoft's May 2026 security updates, including SharePoint Server 2016 / SharePoint Enterprise Server 2016, SharePoint Server 2019, and SharePoint Server Subscription Edition.
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No public exploit code observed for this vulnerability.
Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.
Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.
9 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
A SharePoint-related CVE mentioned only as another issue covered by the same cumulative update.
Another SharePoint-related CVE mentioned only as part of the cumulative May 2026 update bundle; no technical details are provided in the content.
A remote code execution vulnerability in Microsoft SharePoint caused by deserialization of untrusted data. It allows an authenticated attacker with low privileges to execute code over the network and requires user interaction.
A Microsoft SharePoint Server remote code execution vulnerability addressed by this security update.
Query your assets running an affected version, and investigate the blast radius.
Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.