CVE-2025-71276: Alinto SOGo XSS Vulnerability

CVE-2025-71276 Overview

SOGo before version 5.12.5 is vulnerable to a Cross-Site Scripting (XSS) attack affecting events, tasks, and contacts categories functionality. This client-side injection vulnerability allows attackers to execute malicious scripts in the context of a victim's browser session when interacting with specially crafted category entries within the SOGo groupware application.

Critical Impact

Attackers can inject malicious scripts through events, tasks, and contacts categories, potentially stealing session cookies, capturing user credentials, or performing unauthorized actions on behalf of authenticated users.

Affected Products

• Alinto SOGo versions prior to 5.12.5

Discovery Timeline

• 2026-03-22 - CVE CVE-2025-71276 published to NVD
• 2026-03-23 - Last updated in NVD database

Technical Details for CVE-2025-71276

Vulnerability Analysis

This vulnerability is classified as CWE-79 (Improper Neutralization of Input During Web Page Generation), commonly known as Cross-Site Scripting. The flaw exists in how SOGo handles user-supplied input within category fields for events, tasks, and contacts. When users create or modify categories, the application fails to properly sanitize or encode the input before rendering it back in the browser.

The network-based attack vector allows remote exploitation without requiring authentication, though user interaction is necessary for successful exploitation. An attacker must convince a victim to interact with a malicious category entry, such as viewing an event or task that contains the injected payload. The scope of the vulnerability extends beyond the vulnerable component, potentially allowing an attacker to affect resources and sessions outside of SOGo's immediate security boundary.

Root Cause

The root cause stems from insufficient input validation and output encoding in the category handling functionality of SOGo's web interface. When category names are processed and displayed, the application does not properly escape special HTML characters such as <, >, ", and '. This allows JavaScript code embedded in category fields to be interpreted and executed by the victim's browser rather than being rendered as plain text.

Attack Vector

The attack vector for this vulnerability involves network-based exploitation through the SOGo web interface. An attacker can craft malicious category entries containing JavaScript payloads and share them with potential victims through collaborative features such as shared calendars, event invitations, or contact sharing. When a victim views or interacts with the compromised category data, the malicious script executes within their authenticated session.

The vulnerability allows for reflected or stored XSS scenarios depending on how the malicious category data is introduced and persisted within the application. Successful exploitation could lead to session hijacking, phishing attacks, keylogging, or unauthorized actions performed under the victim's identity.

Detection Methods for CVE-2025-71276

Indicators of Compromise

• Presence of suspicious HTML tags or JavaScript code within event, task, or contact category fields in SOGo databases
• Unexpected script execution errors or browser console warnings when viewing categories
• User reports of unusual browser behavior or popup dialogs when accessing SOGo calendar or contacts
• Log entries showing category data containing encoded script patterns such as %3Cscript%3E or HTML entity-encoded payloads

Detection Strategies

• Implement web application firewall (WAF) rules to detect and block XSS payloads in HTTP requests targeting SOGo category endpoints
• Monitor application logs for requests containing script tags, event handlers (e.g., onerror, onload), or JavaScript pseudo-protocols in category-related API calls
• Deploy browser-based Content Security Policy (CSP) headers to prevent inline script execution and report violations

Monitoring Recommendations

• Enable verbose logging for SOGo web server components to capture full request payloads
• Configure SIEM rules to alert on suspicious patterns in category field values, particularly HTML/JavaScript injection attempts
• Review database entries periodically for anomalous category names containing HTML markup or script content

How to Mitigate CVE-2025-71276

Immediate Actions Required

• Upgrade SOGo to version 5.12.5 or later immediately to remediate this vulnerability
• Review existing calendar events, tasks, and contacts for potentially malicious category entries
• Implement Content Security Policy (CSP) headers with strict script-src directives as a defense-in-depth measure
• Consider temporarily restricting category creation/modification permissions for untrusted users until patching is complete

Patch Information

Alinto has released a security fix addressing this vulnerability. The patch is available through the GitHub Commit Update. Organizations should update to SOGo version 5.12.5 or later which includes proper input sanitization and output encoding for category fields.

Workarounds

• Deploy a web application firewall (WAF) with XSS detection rules to filter malicious payloads before they reach SOGo
• Implement strict Content Security Policy headers to prevent inline script execution: Content-Security-Policy: default-src 'self'; script-src 'self'
• Restrict access to SOGo to trusted networks or users via reverse proxy authentication while awaiting patch deployment
• Sanitize existing database entries to remove any potentially malicious category values

# Example Content Security Policy configuration for Apache
# Add to SOGo virtual host configuration
Header always set Content-Security-Policy "default-src 'self'; script-src 'self'; style-src 'self' 'unsafe-inline'; img-src 'self' data:; frame-ancestors 'self';"
Header always set X-Content-Type-Options "nosniff"
Header always set X-XSS-Protection "1; mode=block"