CVE-2026-4107: ManageEngine Exchange Reporter XSS Flaw

CVE-2026-4107 Overview

CVE-2026-4107 is a Stored Cross-Site Scripting (XSS) vulnerability affecting Zohocorp ManageEngine Exchange Reporter Plus versions prior to build 5802. The vulnerability exists within the Folder Message Count and Size report functionality, where user-supplied input is not properly sanitized before being stored and rendered back to users. This allows attackers to inject malicious scripts that execute in the context of other users' browser sessions when they view the affected report.

Critical Impact

Authenticated attackers can inject persistent malicious scripts into the application, potentially leading to session hijacking, credential theft, and unauthorized actions performed on behalf of legitimate users accessing Exchange Reporter Plus reports.

Affected Products

• Zohocorp ManageEngine Exchange Reporter Plus versions before build 5802
• Zohocorp ManageEngine Exchange Reporter Plus version 5.8 (build 5800)
• Zohocorp ManageEngine Exchange Reporter Plus version 5.8 (build 5801)

Discovery Timeline

• April 3, 2026 - CVE-2026-4107 published to NVD
• April 3, 2026 - Last updated in NVD database

Technical Details for CVE-2026-4107

Vulnerability Analysis

This Stored XSS vulnerability (CWE-79) affects the Folder Message Count and Size report functionality in ManageEngine Exchange Reporter Plus. The application fails to properly sanitize and encode user-controlled input before storing it in the database and subsequently rendering it in the report output. When authenticated users view the affected report, the malicious payload executes within their browser session.

The vulnerability requires low privileges to exploit but does require user interaction, as a victim must view the compromised report for the payload to execute. The scope is changed, meaning the vulnerable component can impact resources beyond its security context—specifically, the attacker can affect the victim's browser session and potentially access other applications within the same origin.

Root Cause

The root cause of this vulnerability is improper input validation and output encoding within the Folder Message Count and Size report module. User-supplied data is stored without adequate sanitization and later rendered in HTML context without proper encoding, allowing JavaScript code injection. This represents a classic failure to implement defense-in-depth input validation strategies.

Attack Vector

The attack is network-accessible and requires an authenticated attacker with low-level privileges to inject malicious content into the report data fields. The exploitation flow involves:

1. An authenticated attacker accesses the Folder Message Count and Size report functionality
2. The attacker injects a malicious JavaScript payload into a field that gets stored in the application database
3. When another user (potentially an administrator) views the affected report, the stored payload executes in their browser
4. The attacker can then steal session tokens, perform actions as the victim, or redirect users to malicious sites

The vulnerability can be exploited by injecting JavaScript payloads through input fields associated with the report. When the report is rendered, the unsanitized payload executes in the victim's browser context. For detailed technical information, refer to the ManageEngine Security Advisory.

Detection Methods for CVE-2026-4107

Indicators of Compromise

• Presence of encoded or obfuscated JavaScript patterns in report data fields or database entries
• Unusual <script> tags, event handlers (e.g., onerror, onload), or JavaScript protocol handlers in stored report content
• Web application logs showing suspicious payloads containing XSS attack patterns in HTTP requests

Detection Strategies

• Implement Web Application Firewall (WAF) rules to detect and block common XSS payload patterns in incoming requests
• Monitor application logs for anomalous input patterns targeting the Folder Message Count and Size report functionality
• Deploy endpoint detection solutions to identify suspicious browser behavior resulting from script injection attacks

Monitoring Recommendations

• Enable verbose logging for all report generation and viewing activities in Exchange Reporter Plus
• Configure alerts for detection of HTML/JavaScript tags in report input fields
• Monitor for unusual administrative actions that may indicate session compromise following XSS exploitation

How to Mitigate CVE-2026-4107

Immediate Actions Required

• Upgrade ManageEngine Exchange Reporter Plus to build 5802 or later immediately
• Review existing report data for potentially injected malicious content
• Implement Content Security Policy (CSP) headers to reduce the impact of any successful XSS attacks
• Educate users about the risks of viewing reports from untrusted or unverified sources

Patch Information

Zohocorp has released ManageEngine Exchange Reporter Plus build 5802 which addresses this vulnerability. Organizations should apply this update as soon as possible. For detailed patch information and download links, refer to the ManageEngine Security Advisory.

Workarounds

• Restrict access to the Folder Message Count and Size report functionality to trusted users only until the patch is applied
• Implement network segmentation to limit access to the Exchange Reporter Plus application
• Deploy browser-based XSS protection mechanisms and ensure users have modern browsers with built-in XSS filtering enabled
• Configure strict Content Security Policy headers at the web server level to mitigate script execution

# Example: Add CSP header in Apache configuration as temporary mitigation
# Add to httpd.conf or .htaccess
Header set Content-Security-Policy "default-src 'self'; script-src 'self'; style-src 'self' 'unsafe-inline'"