CVE-2025-70844: yaffa v2.0.0 XSS Vulnerability

CVE-2025-70844 Overview

CVE-2025-70844 is a Cross-Site Scripting (XSS) vulnerability affecting yaffa v2.0.0, a financial management tool. An attacker can inject malicious JavaScript into the "Add Account Group" function on the account-group page, allowing execution of arbitrary script in the context of users who view the affected page. This stored XSS vulnerability enables attackers to steal session tokens, perform unauthorized actions, or redirect users to malicious sites.

Critical Impact

Attackers can execute arbitrary JavaScript in victims' browsers when they view the compromised account-group page, potentially leading to session hijacking, credential theft, or phishing attacks against users of the application.

Affected Products

• yaffa v2.0.0

Discovery Timeline

• April 7, 2026 - CVE-2025-70844 published to NVD
• April 9, 2026 - Last updated in NVD database

Technical Details for CVE-2025-70844

Vulnerability Analysis

This vulnerability is classified as CWE-94 (Improper Control of Generation of Code) and manifests as a stored Cross-Site Scripting (XSS) flaw. The application fails to properly sanitize user input in the "Add Account Group" functionality before storing it in the database and rendering it back to users. When a victim navigates to the account-group page containing the malicious payload, the injected JavaScript executes within their browser session with full access to the page's DOM and the user's authentication context.

The attack requires no authentication from the attacker (though application access may be needed to submit the malicious input), but does require user interaction in the form of a victim viewing the compromised page. The scope is changed, meaning the vulnerable component (the web application) impacts resources beyond its security scope (the user's browser session).

Root Cause

The root cause is improper input validation and output encoding in the account group creation functionality. The application accepts user-supplied data for account group names or descriptions without sanitizing special characters or encoding output when rendering the stored data. This allows HTML and JavaScript code to be interpreted by the browser rather than displayed as plain text.

Attack Vector

The attack is network-based and exploits the "Add Account Group" feature on the account-group page. An attacker submits a crafted payload containing malicious JavaScript when creating a new account group. The payload is stored in the application's database. When any user subsequently views the account-group page, the malicious script executes in their browser context.

The vulnerability enables attackers to:

• Steal session cookies and authentication tokens
• Perform actions on behalf of authenticated users
• Modify page content to conduct phishing attacks
• Redirect users to malicious external sites
• Capture keystrokes and form data entered on the page

For detailed technical analysis and proof-of-concept information, see the vulnerability research documentation.

Detection Methods for CVE-2025-70844

Indicators of Compromise

• Presence of <script> tags or JavaScript event handlers (e.g., onerror, onload, onclick) in account group names or descriptions
• Unusual database entries containing encoded JavaScript payloads or HTML entities
• Web application firewall logs showing XSS pattern matches on account-group related endpoints
• User reports of unexpected browser behavior or redirects when viewing account group pages

Detection Strategies

• Implement web application firewall (WAF) rules to detect and block common XSS payloads in POST requests to account group endpoints
• Enable Content Security Policy (CSP) violation reporting to detect inline script execution attempts
• Monitor HTTP request logs for suspicious payloads containing JavaScript keywords, HTML tags, or encoded variants
• Perform regular database audits to identify stored XSS payloads in account group tables

Monitoring Recommendations

• Configure application logging to capture all input submitted to the account group creation endpoint
• Set up alerts for CSP violations that may indicate XSS exploitation attempts
• Monitor for unusual patterns in account group data such as entries with HTML-like content
• Implement real-time scanning of user-generated content before storage and display

How to Mitigate CVE-2025-70844

Immediate Actions Required

• Apply input validation to reject or sanitize HTML and JavaScript characters in all user-supplied fields
• Implement proper output encoding (HTML entity encoding) when rendering user-generated content
• Deploy Content Security Policy headers with strict script-src directives to prevent inline script execution
• Review and sanitize existing database records that may contain malicious payloads

Patch Information

Monitor the official yaffa repository for security updates and patches addressing this vulnerability. Users should upgrade to patched versions as soon as they become available.

Workarounds

• Implement server-side input validation to strip or encode HTML special characters (<, >, ", ', &) from account group inputs
• Deploy a Web Application Firewall (WAF) with XSS protection rules enabled for the application
• Add Content Security Policy headers: Content-Security-Policy: default-src 'self'; script-src 'self' to prevent inline script execution
• Restrict access to account group management features to trusted administrators only until a patch is available
• Consider using a JavaScript sanitization library to clean user input before storage and display

# Example Content Security Policy header configuration for Apache
# Add to .htaccess or httpd.conf
Header set Content-Security-Policy "default-src 'self'; script-src 'self'; style-src 'self' 'unsafe-inline'; img-src 'self' data:; object-src 'none';"

# Example for Nginx - add to server block
add_header Content-Security-Policy "default-src 'self'; script-src 'self'; style-src 'self' 'unsafe-inline'; img-src 'self' data:; object-src 'none';";