CVE-2025-54132: Cursor Code Editor Disclosure Vulnerability

CVE-2025-54132 Overview

CVE-2025-54132 is a Server-Side Request Forgery (SSRF) vulnerability in Cursor, an AI-powered code editor developed by Anysphere. The vulnerability exists in versions below 1.3 and stems from how the application renders Mermaid diagrams in the chat interface. An attacker can exploit this flaw to exfiltrate sensitive information to an external attacker-controlled server through embedded image fetches, triggered after successfully performing a prompt injection attack.

Critical Impact

Successful exploitation allows attackers to exfiltrate sensitive data including source code, credentials, and other confidential information from developer workstations to attacker-controlled servers via prompt injection.

Affected Products

• Anysphere Cursor versions below 1.3
• Cursor AI code editor with Mermaid diagram rendering functionality
• Any installation using the vulnerable chat interface with image embedding support

Discovery Timeline

• 2025-08-01 - CVE-2025-54132 published to NVD
• 2025-08-25 - Last updated in NVD database

Technical Details for CVE-2025-54132

Vulnerability Analysis

This vulnerability combines two attack techniques: Server-Side Request Forgery (SSRF) and prompt injection. The Mermaid diagram rendering component in Cursor allows embedding external images which are then fetched and displayed within the chat interface. This functionality, while intended for legitimate diagram rendering, creates an attack surface where malicious content can trigger outbound requests to attacker-controlled servers.

The vulnerability is classified under CWE-918 (Server-Side Request Forgery), indicating that the application can be manipulated into making HTTP requests to arbitrary destinations. What makes this particularly dangerous in the context of an AI-powered code editor is the potential for sensitive developer data—including source code, API keys, and environment variables—to be exfiltrated during these requests.

Root Cause

The root cause lies in insufficient input validation and sanitization of Mermaid diagram content before rendering. The chat interface trusts embedded image URLs within Mermaid syntax without properly restricting or validating the destination servers. When combined with the AI chat functionality, prompt injection attacks can manipulate the model into generating or processing Mermaid content containing malicious image references that trigger data exfiltration.

Attack Vector

The attack requires an adversary to successfully inject a malicious prompt into the Cursor AI system. This can occur through multiple vectors:

1. Malicious web content - A developer visits a webpage containing crafted content that gets processed by the AI
2. Compromised source code - Code repositories containing embedded prompt injection payloads
3. Malicious image uploads - Images with embedded metadata containing injection payloads
4. Model hallucination/backdoor - A compromised or manipulated AI model could autonomously trigger the exploit

Once the prompt injection succeeds, the AI generates Mermaid diagram syntax containing an image reference pointing to an attacker-controlled server. When rendered in the chat interface, Cursor fetches the image, and sensitive context data may be appended to the request URL or headers, allowing the attacker to capture it.

Detection Methods for CVE-2025-54132

Indicators of Compromise

• Unexpected outbound HTTP/HTTPS requests from Cursor to unfamiliar external domains
• Mermaid diagram content in chat logs containing suspicious image URLs with query parameters
• Network traffic showing data exfiltration patterns with encoded or obfuscated URL parameters
• Unusual AI chat interactions that generate diagram content without user initiation

Detection Strategies

• Monitor outbound network connections from the Cursor application process for connections to unknown or suspicious domains
• Implement DNS logging to identify resolution requests for potentially malicious domains originating from developer workstations
• Review application logs for Mermaid diagram rendering events, particularly those containing external image references
• Deploy endpoint detection rules to alert on URL patterns typical of data exfiltration attempts

Monitoring Recommendations

• Enable network traffic monitoring on developer workstations with specific attention to the Cursor application
• Implement egress filtering to block or alert on unexpected outbound connections from development tools
• Configure SIEM rules to correlate Cursor process activity with unusual network behaviors
• Establish baseline network behavior for developer environments to identify anomalous exfiltration attempts

How to Mitigate CVE-2025-54132

Immediate Actions Required

• Upgrade Cursor to version 1.3 or later immediately
• Audit recent AI chat interactions for suspicious Mermaid diagram content containing external URLs
• Review network logs for potential data exfiltration from developer machines running vulnerable versions
• Consider temporarily disabling Mermaid rendering functionality if immediate upgrade is not possible

Patch Information

Anysphere has addressed this vulnerability in Cursor version 1.3. The fix implements proper validation and sanitization of embedded content within Mermaid diagrams, preventing unauthorized external image fetches that could be used for data exfiltration. Users should upgrade to version 1.3 or later to receive the security fix. For detailed information about the vulnerability and patch, refer to the GitHub Security Advisory GHSA-43wj-mwcc-x93p.

Workarounds

• Implement network-level egress filtering to block outbound connections from Cursor to untrusted domains
• Use application-level firewalls to restrict Cursor's ability to make external HTTP requests
• Avoid processing untrusted code, images, or web content through the Cursor AI chat interface until the patch is applied
• Monitor and log all outbound network activity from development environments for forensic analysis