CVE-2026-63108 is a command injection vulnerability in RooCodeInc's Roo-Code product through version 3.54.0. The vulnerability arises because the command parser in parse-command.ts replaces parameter expansions with opaque placeholders before extracting command substitutions. This parsing approach causes the containsDangerousSubstitution guard to overlook nested command substitutions embedded inside parameter expansion defaults. As a result, attackers can craft inputs that bypass the allowlist/denylist enforcement in the auto-approve execute feature. The outer command prefix appears allowlisted, so the nested malicious commands are auto-approved and executed by the shell via execa, enabling arbitrary command execution.

An attacker can achieve arbitrary command execution on systems running vulnerable versions of Roo-Code by bypassing input filtering mechanisms. This can lead to unauthorized code execution with the privileges of the application, potentially compromising system integrity and confidentiality. The vulnerability has a high CVSS 4.0 score of 7.7, indicating significant risk if exploited.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is available, avoid using the auto-approve execute feature or restrict its usage to trusted inputs only. Monitor vendor communications for updates on patches or official mitigations.