Description

Improper neutralization of input during web page generation ('cross-site scripting') in Microsoft Exchange Server allows an authorized attacker to perform spoofing over a network.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "7.3",
  "pubDate": "2026-08-11T17:18:45.447Z",
  "pubdate": "2026-08-11T17:18:45.447Z",
  "executiveSummary": "A cross-site scripting vulnerability exists within Microsoft Exchange Server due to the improper neutralization of user-supplied input during web page generation. This security flaw enables an authorized adversary to execute arbitrary script code within the context of a victim's browser session, leading to spoofing attacks over a network.\nThe primary impact of this vulnerability involves the potential manipulation of web interface content, unauthorized user action execution, and session compromise. The affected product is Microsoft Exchange Server. Risk implications are significant for enterprise environments, as compromised Exchange interfaces can serve as a vector for further internal network reconnaissance or credential harvesting.\nExploitation requires the attacker to possess authorization within the network and the ability to interact with the vulnerable web component of Microsoft Exchange Server. The attack vector relies on network connectivity to inject malicious payloads that the server subsequently renders unsanitized to other users.",
  "technicalDetails": "The root cause of this vulnerability is classified under CWE-79, which is the improper neutralization of input during web page generation, commonly known as cross-site scripting (XSS). Specifically, the vulnerable component within Microsoft Exchange Server fails to adequately validate, sanitize, or encode input parameters supplied by users before dynamically incorporating them into HTTP responses or rendered web pages.\nAuthentication and privilege requirements dictate that the attacking actor must be an authorized user within the target network environment. While authentication is required, the execution of the attack leverages the trust established between the user's browser and the Microsoft Exchange Server web application interface.\nThe attack flow proceeds in a step-by-step manner. First, the authorized attacker crafts a malicious payload containing executable script code, such as JavaScript, designed to manipulate the Document Object Model (DOM) or spoof interface elements. Second, the attacker injects this payload into the vulnerable Microsoft Exchange Server input vector over the network. Third, the Exchange application incorporates the unsanitized input directly into web pages generated for other users.\nWhen a victim accesses the affected web page, the browser parses and executes the embedded payload within the security context of the victim's active session. This payload behavior allows the script to interact with the application on behalf of the user, potentially forging requests, displaying misleading interface elements to facilitate spoofing, or exfiltrating sensitive session data.\nThe network exposure is restricted to network-accessible instances of Microsoft Exchange Server hosting the vulnerable web application components. Post-exploitation impact encompasses localized session hijacking, interface spoofing, and potential escalation of unauthorized activities depending on the privileges of the interacting victim."
}