Attack Chain

1. Attacker authenticates to the POST /openc3-api/auth/verify endpoint to obtain a valid session token.
2. Attacker invokes the set_setting JSON-RPC method via POST /openc3-api/api to set the pypi_url parameter to a malicious payload (e.g., https://pypi.org ; <command> ; #).
3. Attacker prepares a malicious plugin gem containing a requirements.txt or pyproject.toml file to trigger the Python installation logic.
4. Attacker uploads the malicious plugin via POST /openc3-api/plugins.
5. Attacker triggers the plugin installation using the hash obtained from the upload via POST /openc3-api/plugins/install/<id>.
6. The openc3/lib/openc3/models/plugin_model.rb script executes the injected payload through the Ruby backtick operator, which spawns /bin/sh -c.
7. The operating system executes the malicious command with the privileges of the openc3 service user.

Impact

Successful exploitation allows for full control of the openc3 service account inside the container. This leads to the exfiltration or modification of telemetry and commanding data, compromise of cloud storage (S3) credentials, and access to internal Redis/Valkey configuration passwords. This vulnerability enables lateral movement or deeper persistence within the scope of the affected container.

Recommendation

1. Upgrade OpenC3 to a patched version once available; monitor vendor security advisories for the specific release addressing CVE-2026-77601.
2. Apply the code-level mitigation by replacing the Ruby backtick execution in plugin_model.rb with an OpenC3::ProcessManager.spawn call using an argument array to prevent shell interpretation.
3. Implement input validation on the pypi_url setting to restrict values to legitimate HTTP or HTTPS URLs.
4. Review audit logs for anomalous set_setting calls involving JSON-RPC where the parameter values contain shell metacharacters like ;, &, |, or backticks.