CVE-2026-42548: Flightphp Core

High severity, CVSS 8.6. EPSS: 0.5% chance of exploitation in the next 30 days.

Flight is an extensible micro-framework for PHP. Prior to 3.18.1, Flight::jsonp() concatenates the ?jsonp= query parameter directly into an application/javascript response body without validating that the value is a legal JavaScript identifier. An attacker can inject arbitrary JavaScript that executes in the response origin, enabling reflected cross-site scripting. This vulnerability is fixed in 3.18.1.

Affected products

• Flightphp Core: before 3.18.1 (fixed in 3.18.1)

Published 2026-05-13. Last modified 2026-06-17.