CVE-2022-38900: Decode-uri-component DoS Vulnerability

CVE-2022-38900 Overview

CVE-2022-38900 is an Improper Input Validation vulnerability affecting the decode-uri-component npm package version 0.2.0. This widely-used JavaScript library is responsible for decoding percent-encoded characters in URI components and is a common dependency in many Node.js applications. The vulnerability allows remote attackers to cause a Denial of Service (DoS) condition by supplying specially crafted input to the decoding function.

Critical Impact

Remote attackers can exploit this vulnerability to crash or hang Node.js applications that process untrusted URI input, potentially causing service outages and affecting application availability.

Affected Products

• decode-uri-component version 0.2.0
• Applications using query-string library (which depends on decode-uri-component)
• Fedora distributions containing vulnerable package versions

Discovery Timeline

• 2022-11-28 - CVE-2022-38900 published to NVD
• 2025-04-25 - Last updated in NVD database

Technical Details for CVE-2022-38900

Vulnerability Analysis

The vulnerability stems from improper input validation (CWE-20) within the decode-uri-component library. When the library processes specially crafted URI-encoded strings, it fails to properly validate and handle malformed input sequences. This allows an attacker to trigger resource exhaustion or infinite processing loops, leading to application unresponsiveness or crashes.

The vulnerability is exploitable over the network without requiring authentication or user interaction, making it particularly dangerous for publicly accessible web applications and APIs that process user-supplied URI parameters.

Root Cause

The root cause lies in insufficient validation of input strings before processing percent-encoded sequences. The decoding logic does not adequately handle edge cases involving malformed or deliberately crafted URI component strings. When encountering these malicious inputs, the algorithm can enter computationally expensive operations or infinite loops, consuming excessive CPU resources and blocking the event loop in Node.js applications.

Attack Vector

The attack vector is network-based, allowing remote exploitation. An attacker can craft a malicious URI-encoded string and submit it to any application endpoint that processes URI components using the vulnerable library. Common attack surfaces include:

• Query string parameters in web applications
• API endpoints accepting URL-encoded data
• Any input processing pipeline using the query-string library or similar dependencies

The vulnerability can be triggered by passing malicious input to the decodeURIComponent wrapper function, causing the application to become unresponsive as it attempts to process the crafted string.

Detection Methods for CVE-2022-38900

Indicators of Compromise

• Unusual CPU spikes or resource exhaustion on Node.js application servers
• Application hangs or timeouts when processing specific HTTP requests
• Increased response times or timeouts on endpoints handling URL-encoded parameters
• Event loop blocking indicators in Node.js monitoring tools

Detection Strategies

• Audit package.json and package-lock.json for decode-uri-component version 0.2.0 dependencies
• Use npm audit or yarn audit to identify vulnerable packages in the dependency tree
• Monitor for applications using query-string library which depends on the vulnerable package
• Implement application performance monitoring to detect unusual processing delays

Monitoring Recommendations

• Enable Node.js process monitoring for event loop lag and CPU utilization anomalies
• Set up alerts for request timeout increases on endpoints processing URI parameters
• Monitor web application firewall logs for requests with unusual URL-encoded patterns
• Review dependency scanning tool results regularly for this and similar supply chain vulnerabilities

How to Mitigate CVE-2022-38900

Immediate Actions Required

• Update decode-uri-component to a patched version (0.2.1 or later)
• Run npm update decode-uri-component or yarn upgrade decode-uri-component to update the dependency
• Review and update all transitive dependencies that may include the vulnerable version
• Consider implementing input length limits on URI parameters as a defense-in-depth measure

Patch Information

The vulnerability has been addressed in versions of decode-uri-component released after 0.2.0. Security updates have been distributed through multiple channels including Fedora package announcements. Detailed technical discussion of the vulnerability can be found in the decode-uri-component GitHub Issue #5 and the related query-string GitHub Issue #345.

Workarounds

• Implement request payload size limits to reduce the impact of malicious inputs
• Add input validation and sanitization before passing data to URI decoding functions
• Use rate limiting to mitigate potential DoS attacks exploiting this vulnerability
• Consider using alternative URI decoding libraries that are not affected by this vulnerability

# Update the vulnerable package
npm update decode-uri-component

# Verify the installed version is patched
npm ls decode-uri-component

# Run security audit to check for other vulnerabilities
npm audit