CVE-2025-2204: Tap&Sign Cross-Site Scripting Vulnerability

CVE-2025-2204 Overview

CVE-2025-2204 is a Cross-Site Scripting (XSS) vulnerability affecting Tap&Sign, a product developed by Tapandsign Technologies Software Inc. The vulnerability stems from improper neutralization of input during web page generation, allowing attackers to inject malicious scripts into web pages viewed by other users.

Critical Impact

This XSS vulnerability could allow attackers to execute arbitrary JavaScript in the context of authenticated user sessions, potentially leading to session hijacking, data theft, or unauthorized actions on behalf of victims.

Affected Products

• Tap&Sign versions through 23012026

Discovery Timeline

• 2026-01-23 - CVE-2025-2204 published to NVD
• 2026-01-26 - Last updated in NVD database

Note: The vendor was contacted early about this disclosure but did not respond in any way.

Technical Details for CVE-2025-2204

Vulnerability Analysis

This vulnerability is classified as CWE-79 (Improper Neutralization of Input During Web Page Generation), commonly known as Cross-Site Scripting (XSS). The flaw exists in the Tap&Sign application where user-supplied input is not properly sanitized or encoded before being rendered in web pages.

XSS vulnerabilities occur when an application includes untrusted data in a web page without proper validation or escaping. In this case, the Tap&Sign application fails to neutralize special characters that could be interpreted as executable code by the victim's browser. The vulnerability requires high privileges to exploit but can be triggered over the network without user interaction.

Root Cause

The root cause of CVE-2025-2204 is insufficient input validation and output encoding in the Tap&Sign application. When user-controlled data is reflected or stored without proper sanitization, malicious scripts can be injected and executed in the browser context of users viewing the affected pages.

The application fails to implement proper security controls such as:

• Input validation to reject or sanitize potentially dangerous characters
• Output encoding to ensure user data is rendered as text rather than executable code
• Content Security Policy (CSP) headers to mitigate script execution

Attack Vector

The attack vector for this vulnerability is network-based. An attacker with elevated privileges can inject malicious JavaScript code through vulnerable input fields or parameters in the Tap&Sign application. When other users access the affected pages, the injected script executes in their browser session.

The exploitation mechanism involves crafting specially formatted input containing JavaScript payloads that bypass any existing input filters. Once the malicious content is stored or reflected by the application, it executes automatically when rendered in a victim's browser, potentially allowing the attacker to steal session tokens, modify page content, or perform actions on behalf of the victim.

Detection Methods for CVE-2025-2204

Indicators of Compromise

• Unexpected JavaScript code or HTML tags appearing in application data fields
• Suspicious script execution in browser developer console logs
• Unusual network requests to external domains from user browsers when accessing Tap&Sign
• Anomalous user activity patterns suggesting session hijacking

Detection Strategies

• Deploy Web Application Firewalls (WAF) with XSS detection rules to identify and block malicious payloads
• Implement client-side monitoring for suspicious DOM modifications or script injections
• Review application logs for input containing common XSS patterns such as <script>, javascript:, or event handlers
• Monitor for unusual outbound connections from client browsers that may indicate data exfiltration

Monitoring Recommendations

• Enable detailed logging for all user input fields in the Tap&Sign application
• Configure security information and event management (SIEM) systems to alert on XSS attack patterns
• Implement real-time browser security monitoring to detect script injection attempts
• Regularly audit stored content for malicious payloads that may have been injected before detection controls were in place

How to Mitigate CVE-2025-2204

Immediate Actions Required

• Restrict access to the Tap&Sign application to only essential personnel until a patch is available
• Implement a Web Application Firewall (WAF) with strict XSS filtering rules in front of the application
• Enable Content Security Policy (CSP) headers to restrict script execution sources
• Audit existing data for potentially malicious stored XSS payloads and sanitize affected records

Patch Information

No vendor patch is currently available. According to the disclosure, the vendor (Tapandsign Technologies Software Inc.) was contacted early about this vulnerability but did not respond. Organizations using affected versions of Tap&Sign (through version 23012026) should implement compensating controls and consider alternative solutions if the vendor does not provide a security update.

For additional technical details, refer to the USOM Security Advisory TR-26-0004.

Workarounds

• Deploy a reverse proxy or WAF to sanitize incoming requests and filter XSS payloads before they reach the application
• Implement browser-side extensions or policies that restrict JavaScript execution on Tap&Sign pages
• Limit user privileges to reduce the attack surface, as exploitation requires high-privilege access
• Consider network segmentation to isolate the Tap&Sign application from sensitive resources

# Example: Apache mod_security XSS protection rule
SecRule REQUEST_COOKIES|REQUEST_COOKIES_NAMES|REQUEST_FILENAME|ARGS_NAMES|ARGS|XML:/* "@rx (?i)<script[^>]*>[\s\S]*?" \
    "id:941110,\
    phase:2,\
    deny,\
    capture,\
    t:none,t:utf8toUnicode,t:urlDecodeUni,t:htmlEntityDecode,t:jsDecode,t:cssDecode,t:removeNulls,\
    msg:'XSS Filter - Category 1: Script Tag Vector',\
    logdata:'Matched Data: %{TX.0} found within %{MATCHED_VAR_NAME}',\
    tag:'application-multi',\
    tag:'language-multi',\
    tag:'attack-xss',\
    severity:'CRITICAL'"