CVE-2026-128083

Laravel is a web application framework. Prior to 12.71.0 and 13.40.0, Laravel's Concurrency::run process driver can treat a forged internal result message in child standard output as framework output. An application route must invoke Concurrency::run, and a task must write attacker-controlled bytes at the start of the child's standard output that form a complete JSON document followed by gzip magic bytes. Under those application-specific conditions, an attacker can forge the internal result message and achieve remote code execution. The affected behavior is not exposed by default and requires application code that routes untrusted input into task output. This issue is fixed in versions 12.71.0 and 13.40.0.