CVE-2025-67843: Mintlify MDX RCE Vulnerability

CVE-2025-67843 Overview

A Server-Side Template Injection (SSTI) vulnerability exists in the MDX Rendering Engine of Mintlify Platform prior to 2025-11-15. This critical vulnerability allows remote attackers to execute arbitrary code on the server through maliciously crafted inline JSX expressions embedded in MDX files. The vulnerability stems from improper validation and sanitization of user-supplied content during the MDX rendering process.

Critical Impact
Remote attackers can achieve full arbitrary code execution on Mintlify servers without requiring authentication, potentially compromising all hosted documentation sites and underlying infrastructure.

Affected Products

Mintlify Platform (all versions before 2025-11-15)
Mintlify MDX Rendering Engine
Documentation sites hosted on Mintlify infrastructure

Discovery Timeline

2025-12-19 - CVE-2025-67843 published to NVD
2026-01-02 - Last updated in NVD database

Technical Details for CVE-2025-67843

Vulnerability Analysis

This Server-Side Template Injection vulnerability exploits the way Mintlify's MDX rendering engine processes inline JSX expressions. MDX is a format that combines Markdown with JSX, allowing for dynamic content rendering. The vulnerability arises because the rendering engine fails to properly sandbox or validate JSX expressions before server-side execution, creating a direct pathway for attackers to inject and execute arbitrary code.

The attack surface is particularly concerning because MDX files are commonly used for documentation content, and the rendering occurs server-side where the injected code runs with the privileges of the server process. This allows attackers to potentially access sensitive data, modify files, execute system commands, or pivot to other systems within the infrastructure.

Root Cause

The root cause is classified under CWE-1336 (Improper Neutralization of Special Elements Used in a Template Engine). The MDX rendering engine does not implement adequate input validation or sandboxing for JSX expressions. When an attacker supplies a malicious MDX file containing crafted JSX code, the rendering engine evaluates these expressions in an unrestricted server-side context, leading to arbitrary code execution.

Attack Vector

The attack is network-based and requires no authentication or user interaction. An attacker can exploit this vulnerability by submitting a specially crafted MDX file containing malicious inline JSX expressions. When the Mintlify platform processes this file, the embedded JavaScript/JSX code executes on the server.

The attack flow typically involves:

Crafting an MDX file with embedded JSX expressions containing malicious JavaScript
Submitting the file through any interface that triggers MDX rendering (documentation uploads, preview features, etc.)
The server-side rendering engine evaluates the JSX, executing the attacker's payload
The attacker gains code execution with server process privileges

For detailed technical analysis and proof-of-concept information, refer to the Kibty Blog Post which provides an in-depth examination of the vulnerability mechanics.

Detection Methods for CVE-2025-67843

Indicators of Compromise

Unexpected MDX files containing complex or obfuscated JSX expressions in documentation repositories
Unusual server-side process spawning or network connections originating from the MDX rendering service
Log entries showing errors or unexpected behavior during MDX file processing
Evidence of file system access or command execution from documentation rendering processes

Detection Strategies

Implement content scanning for MDX files to identify suspicious JSX patterns before rendering
Monitor server-side processes for unexpected child process creation during documentation builds
Deploy application-layer firewalls to inspect and filter malicious MDX content submissions
Enable verbose logging on MDX rendering components to capture anomalous execution patterns

Monitoring Recommendations

Establish baseline behavior for the MDX rendering service and alert on deviations
Monitor outbound network connections from documentation infrastructure for data exfiltration attempts
Implement file integrity monitoring on servers hosting the Mintlify platform
Set up alerts for unusual CPU or memory usage patterns during documentation rendering operations

How to Mitigate CVE-2025-67843

Immediate Actions Required

Upgrade Mintlify Platform to the patched version released on 2025-11-15 or later
Review all MDX files in documentation repositories for potentially malicious JSX expressions
Implement strict input validation for any MDX content before processing
Consider temporarily disabling user-submitted MDX file processing until the patch is applied

Patch Information

Mintlify has addressed this vulnerability in their platform update released on 2025-11-15. Organizations using Mintlify should ensure they are running the latest version. For detailed patch information and update instructions, consult the Mintlify Changelog Documentation and the Mintlify Blog on Security Researchers which discusses their coordinated disclosure process.

Workarounds

Implement strict allowlisting for JSX components and expressions permitted in MDX files
Deploy a Web Application Firewall (WAF) with rules to block suspicious JSX patterns in uploaded content
Isolate the MDX rendering service in a sandboxed environment with minimal privileges
Disable dynamic JSX evaluation and restrict MDX processing to static content only until patching is complete

bash

# Example: Restricting MDX processing permissions (if self-hosted)
# Ensure the rendering service runs with minimal privileges
chmod 500 /opt/mintlify/mdx-renderer
chown mintlify-service:mintlify-service /opt/mintlify/mdx-renderer
# Remove network access if not required
iptables -A OUTPUT -m owner --uid-owner mintlify-service -j DROP