Microsoft Exchange Server Cross-Site Scripting Vulnerability
Microsoft Exchange Server contains a cross-site scripting vulnerability during web page generation in Outlook Web Access and when certain interaction conditions are met, arbitrary JavaScript can be executed in the browser context.
A remote attacker, without authentication, can achieve full data confidentiality loss, arbitrary modification of data. Federal agencies are required to remediate by 2026-05-29 under CISA BOD 22-01.
This is a Cross-Site Scripting (XSS) (CWE-79) vulnerability in Microsoft Microsoft. Improper neutralization of input during web page generation ('cross-site scripting') in Microsoft Exchange Server allows an unauthorized attacker to perform spoofing over a network. Exploitation requires remote network access, low attack complexity, no authentication required, and user interaction required.
📧
Phishing link
🖼
Malicious file
🔓
Server compromised
Probably yes if any of these apply:
CISA added this CVE to the Known Exploited Vulnerabilities catalog on 2026-05-15 based on evidence of active exploitation in the wild. Federal agencies required to remediate by 2026-05-29.
Manual remediation steps
Apply the Vendor Patch
This vulnerability is in the CISA Known Exploited Vulnerabilities catalog — apply the vendor's security update as soon as possible.
CISA required action: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
References
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References