n8n before 1.123.85, 2.x before 2.43.5, and 2.44.x before 2.44.1 contains an OData $filter injection vulnerability in the Microsoft Outlook contact lookup and Microsoft SharePoint v1 item update nodes, which build $filter string literals from expression-bindable parameters without escaping. Attackers who supply untrusted input to such workflows can inject single quotes to dump the bound mailbox's entire contact list or redirect SharePoint writes onto unintended list items within the stored credential's scope.