CVE-2026-109454

Summary

A cross-site scripting (XSS) vulnerability in Microsoft Office SharePoint allows an authenticated attacker to inject malicious scripts into web pages served to other users, enabling credential theft or account takeover via spoofed UI elements.

Exploitability

Exploitation requires low skill and only a valid low-privileged user account plus social engineering to trigger the payload (e.g.,诱使 victim click a crafted link); no special tools are needed.

Blast radius

Successful exploitation could lead to widespread compromise of internal users’ sessions, data exfiltration from SharePoint, or lateral movement within the organization via compromised accounts.

Detection

Monitor SharePoint ULS logs for HTTP POST requests containing unencoded script tags or event handler attributes (e.g., 'onerror=', 'onclick=') in form fields submitted by low-privileged users; also watch for anomalous outbound requests from SharePoint servers to external domains in user-agent or referrer headers.

Prioritized remediation

Apply Microsoft security update MS26-XXXXX (specific patch for CVE-2026-109454) released on [date]; if unavailable, restrict SharePoint access to trusted networks and disable custom script execution via SharePoint Admin Center settings until patched.

Analysis generated locally by garnet-coder (no data left the box). AI-assisted — verify against primary sources before acting.