Bolt CMS core renders content field values through Twig's full application-level Environment without registering a SandboxExtension, as detailed in src/Entity/Field.php. The getTwigValue function calls shouldBeRenderedAsTwig, which permits rendering based on the allow_twig flag and a regex check for characters such as , , or ;. When these conditions are met, the raw field value is compiled and rendered with no sandboxing, exposing the system to potentially dangerous Twig code execution. This vulnerability is tracked as CVE-2026-71291 and classified under CWE-1336. It has a CVSS 3.1 score of 8.8, indicating high severity with network attack vector, low attack complexity, requiring low privileges, no user interaction, and impacts confidentiality, integrity, and availability.

Exploitation of this vulnerability could allow an attacker with low privileges to execute arbitrary Twig code within the Bolt CMS environment, potentially leading to full system compromise including data disclosure, modification, or denial of service. The lack of sandboxing in Twig rendering increases the risk of code injection and execution.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is available, it is recommended to disable the allow_twig flag on content fields where possible to prevent untrusted Twig code execution. Monitor vendor communications for updates regarding patches or official mitigations.