The vulnerability CVE-2026-26996 affects the isaacs minimatch library, a JavaScript utility that converts glob expressions into regular expressions. Versions 10.2.0 and earlier are susceptible to a Regular Expression Denial of Service (ReDoS) attack due to inefficient handling of patterns containing multiple consecutive '*' wildcards followed by a literal character absent from the test string. Each '*' wildcard compiles into a separate non-greedy regex group ([^/]*?), and when the regex engine attempts to match the pattern against a string that does not contain the literal character, it backtracks exponentially across all possible group splits. The time complexity of this backtracking is O(4^N), where N is the number of '*' characters. For example, with 15 '*' characters, a single minimatch() call can take approximately 2 seconds, and with 34, it can hang indefinitely. This behavior can be exploited by an attacker supplying crafted glob patterns as input to applications using minimatch, causing denial of service by exhausting CPU resources. The vulnerability requires no authentication or user interaction and affects any application that uses vulnerable minimatch versions with user-controlled pattern input. The issue was addressed and fixed in minimatch version 10.2.1. The CVSS 4.0 vector indicates network attack vector, low complexity, no privileges or user interaction required, and a high impact on availability.

This vulnerability can lead to denial of service conditions in applications that rely on minimatch for pattern matching, especially when processing user-supplied glob patterns. Attackers can exploit this flaw remotely without authentication or user interaction, causing significant CPU resource exhaustion and application unavailability. This can disrupt services, degrade performance, and potentially lead to cascading failures in systems dependent on these applications. Organizations using minimatch in web servers, build tools, package managers, or any JavaScript-based services that accept glob patterns are at risk. The impact is particularly severe for high-availability environments and critical infrastructure where downtime or degraded service can cause operational and reputational damage. Although no known exploits are reported in the wild yet, the low complexity and high impact make this a critical concern for developers and security teams.

The primary mitigation is to upgrade all instances of the minimatch library to version 10.2.1 or later, where the vulnerability has been fixed. Additionally, applications should implement input validation and sanitization to restrict or reject glob patterns containing excessive consecutive '*' wildcards, especially when followed by literals unlikely to appear in target strings. Rate limiting and resource usage monitoring can help detect and mitigate potential abuse attempts. Developers should audit their codebases and dependencies to identify where minimatch is used and ensure that user-controlled input is never passed unchecked as a pattern argument. Employing Web Application Firewalls (WAFs) or runtime protection tools that can detect abnormal regex processing times may provide additional defense layers. Finally, educating developers about secure pattern usage and the risks of ReDoS attacks is recommended.