[Contribution] Cross-tenant Event Grid Privilege Escalation Vulnerability

[korniko98]

Summary (give a brief description of the issue)

"an Azure Event Grid System Topic vulnerability allowing us to view Event Subscriptions data for all tenants that had an Event Subscription configured due to a flaw in the filtering mechanism Microsoft used for displaying data to their customers. This vulnerability was disclosed through Microsoft Security Response Center as ‘VULN-162828’ which was classified as ‘Critical’ under the ‘Elevation of Privilege’ topic and later disclosed as ‘CVE-2025-59273’."

References (provide links to blogposts, etc.)

https://thecollective.eu/cross-tenant-event-grid-privilege-escalation-vulnerability/