Executive Summary

CVE-2025-26210 is a Cross-Site Scripting (XSS) vulnerability in the DeepSeek AI platform versions R1 through V3.1. It occurs because the platform insecurely handles user input in AI-generated JavaScript code, specifically by using JavaScript's eval() function without proper sanitization. This allows a remote attacker to inject and execute arbitrary JavaScript code via input fields in the web application, leading to unauthorized script execution within the victim's browser. [1]

Useful 0 Not Useful 0

Impact Analysis

This vulnerability can have severe impacts including arbitrary code execution in the victim's browser, theft of sensitive data such as cookies and URLs, and exfiltration of detailed user environment information (e.g., user agent, OS, screen size, CPU cores, RAM, battery status). Attackers can use this to hijack user sessions, steal personal information, and perform further attacks by sending stolen data to attacker-controlled servers. [1]

Useful 0 Not Useful 0

Detection Guidance

This vulnerability can be detected by testing input fields in the DeepSeek AI platform (versions R1 through V3.1) for improper sanitization that allows JavaScript injection. A common detection method is to submit payloads such as `alert('Hacked!')` into form inputs and observe if the script executes. Network monitoring can also reveal suspicious outbound requests (e.g., JavaScript fetch calls) sending data to attacker-controlled servers. There are no specific commands provided, but manual testing with JavaScript injection payloads and monitoring HTTP POST requests to unknown endpoints can help detect exploitation attempts. [1]

Useful 0 Not Useful 0

Mitigation Strategies

Immediate mitigation steps include disabling or restricting the use of AI-generated JavaScript code that uses `eval()` or similar functions on user input, implementing strict input validation and sanitization to prevent injection of malicious scripts, and monitoring network traffic for suspicious data exfiltration attempts. Additionally, applying any available patches or updates from DeepSeek (if released) and restricting access to vulnerable versions (R1 through V3.1) until a fix is available are recommended. [1]

Useful 0 Not Useful 0