CVE-2024-9506: Vue.js parseHTML ReDoS Vulnerability

CVE-2024-9506 Overview

CVE-2024-9506 is a Regular Expression Denial of Service (ReDoS) vulnerability affecting Vue.js, specifically within the parseHTML function. The vulnerability stems from an improper regular expression implementation that can be exploited to cause excessive CPU consumption, potentially leading to application unavailability.

Critical Impact

Attackers can craft malicious input that triggers catastrophic backtracking in Vue's HTML parser, causing denial of service conditions in applications using the affected component.

Affected Products

• Vue.js (versions using vulnerable parseHTML function)
• Applications utilizing Vue's HTML parsing capabilities
• Web applications built with affected Vue.js versions

Discovery Timeline

• 2024-10-15 - CVE CVE-2024-9506 published to NVD
• 2024-10-16 - Last updated in NVD database

Technical Details for CVE-2024-9506

Vulnerability Analysis

This vulnerability is classified under CWE-1333 (Inefficient Regular Expression Complexity), which describes flaws where regular expressions are constructed in a way that allows for catastrophic backtracking. In Vue's parseHTML function, the regex patterns used to parse HTML content contain constructs that, when presented with specially crafted input, can cause the regex engine to enter an exponential time complexity state.

The attack requires network access but has high attack complexity, meaning specific conditions must be met for successful exploitation. The vulnerability impacts availability without affecting confidentiality or integrity of the system.

Root Cause

The root cause lies in the implementation of regular expressions within Vue's parseHTML function. The regex patterns contain nested quantifiers or overlapping alternations that can match the same input in multiple ways. When an attacker provides input that partially matches these patterns, the regex engine exhaustively explores all possible matching combinations, leading to exponential processing time.

Attack Vector

The attack vector is network-based, allowing remote attackers to submit malicious HTML content to applications that process user-supplied HTML through Vue's parsing mechanisms. An attacker would craft a string specifically designed to exploit the vulnerable regex pattern, causing the application to hang or become unresponsive while processing the input.

The exploitation requires finding input strings that maximize backtracking in the vulnerable regular expression. Typically, these strings contain repeated patterns that nearly match the regex but ultimately fail, forcing the engine to try all possible matching paths before determining no match exists.

Detection Methods for CVE-2024-9506

Indicators of Compromise

• Unusual CPU spikes during HTML parsing operations
• Application timeouts or unresponsiveness when processing specific HTML content
• Increased response times for endpoints that utilize Vue's parseHTML function
• Server resource exhaustion events correlated with HTML processing activities

Detection Strategies

• Monitor application performance metrics for anomalous CPU usage patterns during content processing
• Implement request timeout monitoring to detect potential ReDoS attacks
• Review application logs for timeout errors or hung processes related to HTML parsing
• Deploy web application firewall (WAF) rules to detect potentially malicious input patterns

Monitoring Recommendations

• Set up alerting for unusual CPU consumption in Vue.js application instances
• Monitor request duration metrics for endpoints that process user-supplied HTML
• Implement application performance monitoring (APM) to track parsing function execution times
• Configure resource utilization alerts to detect denial of service conditions early

How to Mitigate CVE-2024-9506

Immediate Actions Required

• Audit your Vue.js applications to identify usage of the vulnerable parseHTML function
• Implement input validation and length restrictions on HTML content before parsing
• Consider implementing request timeouts to prevent long-running parsing operations
• Review and update Vue.js dependencies to versions with patched regex implementations

Patch Information

For detailed patch information and affected version specifics, refer to the HeroDevs CVE-2024-9506 Vulnerability advisory. Organizations should consult this resource for the latest guidance on updating to patched versions of Vue.js.

Workarounds

• Implement strict input length limits on HTML content processed through parseHTML
• Use server-side timeout mechanisms to terminate long-running parsing operations
• Consider alternative HTML parsing libraries that do not exhibit ReDoS vulnerabilities
• Deploy rate limiting on endpoints that accept HTML content to reduce attack surface
• Sanitize and validate HTML input before passing to Vue's parsing functions

# Example: Implement request timeout for Node.js applications
# Set server timeout to prevent long-running ReDoS attacks
export SERVER_TIMEOUT=30000
# Configure maximum request body size to limit attack payload
export MAX_BODY_SIZE="100kb"