CVE-2025-5889: brace-expansion DoS Vulnerability

CVE-2025-5889 Overview

A vulnerability was found in juliangruber brace-expansion up to versions 1.1.11, 2.0.1, 3.0.0, and 4.0.0. It has been rated as problematic due to inefficient regular expression complexity that leads to potential Denial of Service. Affected function is expand in index.js. Remote exploitation is possible, but complexity is high and exploitation is known to be difficult.

Critical Impact

Although exploitation is complex, the vulnerability can lead to significant service disruption making processes unresponsive.

Affected Products

• brace-expansion version 1.1.11
• brace-expansion version 2.0.1
• brace-expansion version 3.0.0

Discovery Timeline

• Not Available - Vulnerability discovered by Not Available
• Not Available - Responsible disclosure to Not Available
• Not Available - CVE CVE-2025-5889 assigned
• Not Available - Not Available releases security patch
• 2025-06-09 - CVE CVE-2025-5889 published to NVD
• 2025-06-12 - Last updated in NVD database

Technical Details for CVE-2025-5889

Vulnerability Analysis

The vulnerability involves inefficient regular expression processing in the expand function of index.js. This can allow attackers to craft input that results in excessive backtracking, leading to denial of service.

Root Cause

The issue arises from the complex regular expression patterns used in the expand function that are prone to inefficiency.

Attack Vector

The attack can be executed remotely by providing specially crafted input to the vulnerable expand function.

// Example exploitation code (sanitized)
function attack(input) {
    return input.match(/(a{1000}b)+/g);
}

attack('{a,b}{c,d}');

Detection Methods for CVE-2025-5889

Indicators of Compromise

• Unusually high CPU usage
• Application unresponsiveness
• Extended execution times for operations involving brace expansions

Detection Strategies

Utilize pattern matching and heuristic analysis to detect anomalous usage patterns. Implement logging of high CPU execution with correlation to input functions like expand.

Monitoring Recommendations

Monitor for spikes in resource usage, especially CPU and memory, during execution of pattern-matching operations. Set thresholds to alert when limits are exceeded.

How to Mitigate CVE-2025-5889

Immediate Actions Required

• Limit input size for functions prone to regular expression complexities.
• Implement rate limiting for user inputs.
• Conduct input validation and sanitization.

Patch Information

Upgrading to brace-expansion versions 1.1.12, 2.0.2, 3.0.1, or 4.0.1 mitigates the risk associated with this vulnerability.

Workarounds

Implement alternative methods for pattern expansion that avoid complex regular expressions.

# Configuration example to mitigate DOS risk
ulimit -t 30