picomatch ReDoS and Injection Vulnerabilities

picomatch, a widely-used Node.js glob pattern matching library, contains a Regular Expression Denial of Service (ReDoS) vulnerability when processing crafted extglob patterns such as '+(a|aa)' or nested patterns like '+(+(a))'. The vulnerability affects picomatch versions prior to 4.0.4, 3.0.2, and 2.3.2 (tracked via CPE pkg:npm/picomatch) and allows unauthenticated remote attackers to cause multi-second event-loop blocking with relatively short inputs, resulting in application-wide denial of service. Patches are available from the vendor, and while no KEV listing or EPSS score is provided in the data, the CVSS score of 7.5 (High) reflects the network-accessible, low-complexity attack vector requiring no privileges or user interaction.

picomatch is vulnerable to a method injection vulnerability (CWE-1321) in its POSIX_REGEX_SOURCE object that allows specially crafted POSIX bracket expressions like [[:constructor:]] to reference inherited Object.prototype methods, causing these methods to be stringified and injected into generated regular expressions. This affects all versions of the npm package picomatch prior to 2.3.2, 3.0.2, and 4.0.4, and can cause incorrect glob matching behavior leading to integrity violations where patterns match unintended filenames; while this does not enable remote code execution, it can compromise security-relevant logic in applications using glob matching for filtering, validation, or access control. The vulnerability is not listed in CISA KEV and has no widely published proof-of-concept, but patches are available from the vendor.