CVE-2022-25901: Cookiejar ReDoS Vulnerability Explained

CVE-2022-25901 Overview

CVE-2022-25901 is a Regular Expression Denial of Service (ReDoS) vulnerability affecting versions of the cookiejar package before 2.1.4. The vulnerability exists in the Cookie.parse function, which uses an insecure regular expression that can be exploited to cause excessive CPU consumption, leading to denial of service conditions in applications that depend on this package.

Critical Impact

Applications using vulnerable versions of cookiejar can be rendered unresponsive through crafted input that triggers catastrophic backtracking in the regular expression engine, causing CPU exhaustion and service unavailability.

Affected Products

• cookiejar_project cookiejar (versions before 2.1.4)
• Node.js applications using vulnerable cookiejar versions
• Java applications using cookiejar via WebJars

Discovery Timeline

• 2023-01-18 - CVE-2022-25901 published to NVD
• 2025-02-13 - Last updated in NVD database

Technical Details for CVE-2022-25901

Vulnerability Analysis

This vulnerability is classified under CWE-1333 (Inefficient Regular Expression Complexity). The cookiejar package, a popular Node.js library for managing HTTP cookies, contains a flawed regular expression pattern in its Cookie.parse function. When processing specially crafted cookie strings, the regular expression exhibits catastrophic backtracking behavior—a well-known weakness in regex engines where certain input patterns cause exponential time complexity.

The vulnerability can be exploited remotely without requiring authentication or user interaction. An attacker can send malicious cookie values to any application endpoint that processes cookies using the vulnerable cookiejar library, causing the application to become unresponsive as the CPU becomes consumed by the regex evaluation.

Root Cause

The root cause of this vulnerability lies in the inefficient regular expression pattern used within the Cookie.parse function located in cookiejar.js. The regex contains quantifiers and alternation patterns that, when combined with specific input strings, trigger exponential backtracking. This occurs because the regex engine must explore an exponentially growing number of possible matching paths before determining a final result.

ReDoS vulnerabilities typically arise from regex patterns containing:

• Nested quantifiers (e.g., (a+)+)
• Overlapping alternations with quantifiers
• Greedy quantifiers without proper anchoring

The fix implemented in version 2.1.4 addresses this by optimizing the regular expression to prevent catastrophic backtracking scenarios.

Attack Vector

The attack can be executed remotely over the network. An attacker crafts a malicious cookie string designed to maximize backtracking in the vulnerable regular expression. This string is then sent as part of an HTTP request to an application using the vulnerable cookiejar package. When the application attempts to parse the cookie using Cookie.parse, the regex engine enters an extended computation state, consuming CPU resources and blocking the event loop in Node.js applications.

Since this is a denial of service attack, the primary impact is on availability. No authentication is required, and no user interaction is needed—making it straightforward to exploit against publicly accessible applications.

For technical details on the vulnerable code pattern, refer to the GitHub Cookie Jar Source Code and the Snyk JS Vulnerability Report.

Detection Methods for CVE-2022-25901

Indicators of Compromise

• Unusual CPU spikes on application servers processing HTTP requests
• Application timeouts or unresponsiveness during cookie parsing operations
• Increased request latency or timeout errors in monitoring dashboards
• Event loop blocking in Node.js applications with high event loop lag metrics

Detection Strategies

• Implement dependency scanning using tools like npm audit, Snyk, or OWASP Dependency-Check to identify vulnerable cookiejar versions
• Monitor application performance metrics for abnormal CPU utilization patterns
• Use Software Composition Analysis (SCA) tools in CI/CD pipelines to detect vulnerable dependencies before deployment
• Review application logs for patterns indicating slow request processing related to cookie handling

Monitoring Recommendations

• Configure alerting for CPU utilization thresholds on servers running applications with cookiejar dependencies
• Implement request timeout monitoring to detect requests that hang during processing
• Enable Node.js event loop monitoring to identify blocking operations
• Set up dependency vulnerability alerts through package management tools or security platforms

How to Mitigate CVE-2022-25901

Immediate Actions Required

• Upgrade cookiejar to version 2.1.4 or later immediately
• Audit all projects and dependencies that may include cookiejar as a transitive dependency
• Run npm audit or equivalent dependency scanning to identify affected applications
• Implement rate limiting on endpoints that process cookies to reduce exploitation impact

Patch Information

The vulnerability has been addressed in cookiejar version 2.1.4. The fix optimizes the regular expression in the Cookie.parse function to eliminate the catastrophic backtracking condition. The patch is available through the GitHub Pull Request #39 with the specific fix implemented in commit eaa0002.

For Debian-based systems, refer to the Debian LTS Security Announcement for distribution-specific patch information.

Workarounds

• Implement input validation and length restrictions on cookie values before they reach the cookiejar parsing function
• Add request timeout configurations to limit the impact of ReDoS attacks on application availability
• Consider using alternative cookie parsing libraries that have been audited for ReDoS vulnerabilities
• Deploy Web Application Firewalls (WAF) with rules to detect and block abnormally long or malformed cookie values

# Upgrade cookiejar to patched version
npm update cookiejar

# Verify installed version is 2.1.4 or later
npm list cookiejar

# Run security audit to check for other vulnerabilities
npm audit