The vulnerability CVE-2026-26996 affects the isaacs minimatch library, a utility that converts glob expressions into JavaScript 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, the V8 JavaScript engine performs exponential backtracking across all possible group splits. This results in a time complexity of O(4^N), where N is the number of '*' characters. For example, with 15 '*' characters, a single call to minimatch() can take approximately 2 seconds, and with 34 '*' characters, the process can hang indefinitely. This vulnerability can be exploited remotely without any authentication or user interaction if an application passes user-controlled input as the pattern argument to minimatch(). The issue has been addressed in minimatch version 10.2.1, which optimizes the regex compilation to prevent excessive backtracking. No known exploits have been reported in the wild as of the publication date.

The primary impact of this vulnerability is a denial of service condition caused by excessive CPU consumption during regex evaluation. Applications that use minimatch to process user-supplied glob patterns can be forced into high CPU usage or become unresponsive, leading to service degradation or outages. This can affect web servers, build systems, file watchers, and any JavaScript-based tooling that relies on minimatch for pattern matching. The vulnerability does not directly compromise confidentiality or integrity but can severely impact availability. Attackers can exploit this flaw remotely without authentication or user interaction, making it a significant risk for internet-facing services. Organizations relying on minimatch in critical infrastructure or high-traffic environments may experience operational disruptions, increased resource costs, and potential cascading failures in dependent systems.

To mitigate this vulnerability, organizations should immediately upgrade all instances of the minimatch library to version 10.2.1 or later, where the issue is fixed. Additionally, developers should implement input validation and sanitization to restrict or reject glob patterns containing excessive consecutive '*' wildcards, especially when patterns originate from untrusted sources. Rate limiting and anomaly detection on pattern submission endpoints can help detect and block abuse attempts. For critical systems, consider isolating or sandboxing pattern matching operations to prevent resource exhaustion from impacting other services. Monitoring CPU usage and response times for services using minimatch can provide early warning signs of exploitation attempts. Finally, maintain an inventory of software dependencies to ensure timely updates and vulnerability patching.