CVE-2026-45484 — Sharepoint Server
HIGHCVE-2026-45484 is a high-severity (CVSS 8.8) Deserialization of Untrusted Data vulnerability in microsoft sharepoint server. A fix is available — see the affected versions and patch details below.
Deserialization of untrusted data in Microsoft Office SharePoint allows an authorized attacker to elevate privileges over a network.
Exploitation Status
No confirmed exploitation observed yet
- A successful exploit gives an attacker total control of the affected component, not partial access.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-45484.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2026-45484 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 384,993 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
Description
Deserialization of untrusted data in Microsoft Office SharePoint allows an authorized attacker to elevate privileges over a network.
Affected Products
sharepoint servermicrosoftDetection & mitigation playbook
Vendor / applianceDetect
Inventory every microsoft sharepoint server deployment and check each version against the affected-products list above.
Fix
Apply the microsoft sharepoint server security patch or hotfix for CVE-2026-45484 on the affected version, following the vendor advisory for your exact build.
Workarounds
Do not deserialise data from untrusted sources: where the format allows it, restrict deserialisation to an explicit allowlist of expected types, and prefer a data-only format (JSON, Protobuf) over one that can reconstruct arbitrary objects until you can upgrade. Alongside that, restrict the management interface to trusted networks and apply the vendor's recommended configuration mitigations.
Frequently Asked Questions
Is CVE-2026-45484 being exploited in your environment?
Detect and block the exploit chain at execution, on systems you cannot patch yet.