CVE-2025-41085: Apidog Stored XSS Vulnerability

CVE-2025-41085 Overview

A Stored Cross-Site Scripting (XSS) vulnerability has been identified in Apidog version 2.7.15. The vulnerability exists due to improper sanitization of SVG image uploads. Attackers can embed malicious scripts within SVG files by sending a POST request to the /api/v1/user-avatar endpoint. These malicious scripts are then stored on the server and executed in the browser context of any user who accesses the compromised resource, potentially leading to session hijacking, credential theft, or further malicious actions.

Critical Impact

Stored XSS vulnerabilities allow persistent attacks where malicious scripts execute automatically for every user viewing the compromised content, enabling widespread credential theft, session hijacking, and propagation of further attacks across the platform's user base.

Affected Products

• Apidog version 2.7.15
• Apidog Web Platform (SVG upload functionality)
• Systems utilizing the /api/v1/user-avatar endpoint for avatar uploads

Discovery Timeline

• 2026-02-04 - CVE-2025-41085 published to NVD
• 2026-02-04 - Last updated in NVD database

Technical Details for CVE-2025-41085

Vulnerability Analysis

This stored XSS vulnerability arises from insufficient input validation and sanitization of SVG file uploads within the Apidog web platform. SVG (Scalable Vector Graphics) files are XML-based and can contain embedded JavaScript code within elements such as <script> tags or event handlers like onload, onclick, and similar attributes.

When a user uploads an SVG file as their avatar through the /api/v1/user-avatar endpoint, the application fails to properly sanitize or strip potentially malicious content from the SVG markup. The malicious file is then stored on the server and served to other users who view the attacker's profile or any page displaying the avatar.

The stored nature of this vulnerability makes it particularly dangerous, as the malicious payload persists on the server and executes automatically whenever the compromised resource is accessed. This can affect multiple users without any additional interaction from the attacker after the initial upload.

Root Cause

The root cause of this vulnerability is the lack of proper input validation and content sanitization for SVG file uploads. The application accepts SVG files without stripping dangerous elements such as embedded scripts, event handlers, or external resource references. SVG files, being XML-based, can contain executable JavaScript that browsers will execute when rendering the image.

The vulnerable endpoint /api/v1/user-avatar does not implement content security measures such as:

• Parsing and sanitizing SVG content to remove script elements
• Validating SVG structure against a safe whitelist of allowed elements and attributes
• Converting SVG uploads to safer raster image formats
• Implementing Content-Security-Policy headers to restrict script execution

Attack Vector

The attack is network-based and requires low privileges (an authenticated user account) to execute. The attacker must craft a malicious SVG file containing embedded JavaScript payload and upload it through the avatar functionality. Once stored, the payload executes in the browser context of any victim who views the attacker's avatar, inheriting the victim's session and permissions.

The attack flow involves uploading a crafted SVG containing malicious JavaScript via a POST request to the /api/v1/user-avatar endpoint. The server stores the unsanitized SVG, and when other users browse to a page displaying the attacker's avatar, the SVG is rendered and the embedded script executes in the victim's browser session.

Detection Methods for CVE-2025-41085

Indicators of Compromise

• Presence of SVG files containing <script> tags or JavaScript event handlers in avatar storage directories
• Unusual POST requests to /api/v1/user-avatar with SVG payloads containing encoded or obfuscated JavaScript
• User reports of unexpected browser behavior or session anomalies when viewing specific user profiles
• Web application firewall logs showing blocked XSS patterns in SVG file uploads

Detection Strategies

• Implement web application firewall (WAF) rules to inspect SVG uploads for embedded scripts and event handlers
• Monitor HTTP traffic for POST requests to /api/v1/user-avatar containing suspicious SVG content patterns
• Scan stored avatar files for XML elements associated with script execution such as <script>, onload, onerror, and similar attributes
• Deploy client-side JavaScript monitoring to detect unexpected script execution contexts

Monitoring Recommendations

• Enable detailed logging for all file upload endpoints, particularly /api/v1/user-avatar
• Configure alerting for SVG files containing script-related XML elements or event handlers
• Monitor for unusual patterns of user session activity that could indicate session hijacking
• Review Content-Security-Policy violation reports for script execution anomalies

How to Mitigate CVE-2025-41085

Immediate Actions Required

• Restrict or disable SVG uploads through the /api/v1/user-avatar endpoint until a patch is available
• Scan existing avatar files for malicious SVG content and remove or replace compromised files
• Implement Content-Security-Policy headers with strict script-src directives to limit script execution
• Consider converting all uploaded SVG files to PNG or JPEG format server-side to eliminate script execution risk

Patch Information

Monitor the INCIBE Security Notice for official patch announcements and updates from Apidog. Upgrade to a patched version as soon as one becomes available. Organizations should test any patches in a staging environment before production deployment.

Workarounds

• Disable SVG file uploads entirely and restrict avatar uploads to raster image formats only (PNG, JPEG, GIF)
• Implement server-side SVG sanitization using libraries designed to strip dangerous elements and attributes
• Add strict Content-Security-Policy headers that prevent inline script execution: Content-Security-Policy: default-src 'self'; script-src 'self'; img-src 'self' data:
• Use a sandboxed iframe with sandbox attribute when displaying user-uploaded SVG content to prevent script execution

# Example Content-Security-Policy header configuration for Apache
Header set Content-Security-Policy "default-src 'self'; script-src 'self'; img-src 'self' data:; object-src 'none';"

# Example for Nginx
add_header Content-Security-Policy "default-src 'self'; script-src 'self'; img-src 'self' data:; object-src 'none';";