On July 16, 2025, we observed the first scan targeting SharePoint’s ToolPane.aspx endpoint — a few days before the public disclosure of CVE-2025-53771. This activity serves as an early warning for defenders to look back at their logs for potential exploitation attempts.

CVE-2025-53771 is a recently disclosed vulnerability affecting Microsoft SharePoint, specifically involving the /_layouts/15/ToolPane.aspx page as an initial entry point. It enables attackers to exploit vulnerable SharePoint instances, potentially leading to unauthorized access or remote code execution depending on the configuration.

172.174.82.132 - - [16/Jul/2025:07:31:10 +0000] "GET /_layouts/15/ToolPane.aspx HTTP/1.1" "http://localhost" "Mozilla/5.0"

The above request originated from a Microsoft-owned IP address, suggesting it could be a legitimate internal scan or proactive reconnaissance. Regardless, this early probing — seen days before the CVE was publicly documented — highlights how quickly threat actors and researchers move once a vulnerability is discovered or hinted at.

We strongly recommend defenders and blue teams search their logs for requests to /_layouts/15/ToolPane.aspx starting around mid-July 2025. Even if your SharePoint instance is not vulnerable, these logs can provide crucial insight into scanning behavior and exposure.

This case reiterates the importance of early detection, strong patch management, and visibility into web request patterns. Expect exploitation attempts of CVE-2025-53771 to increase as public PoCs are already available.