Microsoft SharePoint Deserialization RCE
CVE-2026-20963 is a remote code execution vulnerability in Microsoft Office SharePoint caused by deserialization of untrusted data. Microsoft and downstream reporting describe the flaw as affecting SharePoint Server Subscription Edition, SharePoint Server 2019, and SharePoint Enterprise Server 2016. The issue allows attacker-controlled serialized data to be processed by SharePoint in an unsafe manner, resulting in arbitrary code execution in a network-based attack. Available reporting is inconsistent on privileges required: Microsoft/CVE metadata cited in the provided content describes exploitation by an authorized attacker and gives a CVSS v3.1 vector of AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H, while other reporting characterizes it as unauthenticated/unauthorized. Based on the authoritative CVE metadata in the provided content, low privileges are required.
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Impact, mitigation & remediation
What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.
Impact
What an attacker gets, and what they’ve been doing with it.
Mitigation
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Remediation
Patch, then assume compromise.
Exploits
No valid public exploits. Mallory filtered out 1 candidate as fakes, detection scripts, or README-only repos.
All candidate exploits were filtered out by Mallory's validation.
Affected products & vendors
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.
Recent activity
73 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
A vulnerability identified as CVE-2026-20963 affecting SharePoint Server 2019 and possibly other SharePoint products/versions, for which Microsoft released a security update.
A remote code execution vulnerability in Microsoft SharePoint Server caused by deserialization of untrusted data, allowing an unauthenticated attacker to execute arbitrary code remotely via a low-complexity network attack.
A severe vulnerability affecting Microsoft Office SharePoint (details not provided in the content).
A severe vulnerability affecting Microsoft Office SharePoint addressed in Microsoft’s January 2026 Patch Tuesday release.
The version that knows your environment.
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.