CVE-2026-72782

Craft CMS versions >= 5.0.0-RC1 before 5.10.6 and >= 4.0.0-RC1 before 4.18.2 interpolate environment variables and secrets (via ${ENV_VAR} strings in the elementId parameter) into Twig templates before rendering, even when the Twig sandbox is enabled. An authenticated attacker with control panel access can render a malicious sandboxed Twig template and, using a blind error-based technique across many requests, incrementally leak arbitrary environment variables and secrets. These can be abused to forge sessions (via CRAFT_SECURITY_KEY), escalate privileges, and steal database, SMTP, API, or blob storage credentials. Fixed in 5.10.6 and 4.18.2.

Craft CMS versions >= 5.0.0-RC1 before 5.10.6 and >= 4.0.0-RC1 before 4.18.2 interpolate environment variables and secrets (via ${ENV_VAR} strings in the elementId parameter) into Twig templates before rendering, even when the Twig sandbox is enabled. An authenticated attacker with control panel access can render a malicious sandboxed Twig template and, using a blind error-based technique across many requests, incrementally leak arbitrary environment variables and secrets. These can be abused to forge sessions (via CRAFT_SECURITY_KEY), escalate privileges, and steal database, SMTP, API, or blob storage credentials. Fixed in 5.10.6 and 4.18.2.

Environment variables and secrets are interpolated into a Twig template even when the Twig sandbox is enabled, allowing them to be leaked by an authenticated attacker.

The Craft vulnerability CVE-2026-31857 was only patched by applying sandboxed Twig templating. This theoretically protects Craft CMS against RCE attacks, provided the sandbox is enabled and secure, with no known bypasses.

However, the same request parameter elementId, which allows for sandboxed Twig templates to be rendered, also includes functionality that interpolates referenced environment variables. If the parameter includes a string of the form ${ENV_VAR} then the string is replaced with the environment variable or secret from a secrets file with that name.

Afterward, the string is rendered as a Twig template. If the sandbox is disabled, Twig templates can already gain RCE or access environment variables using the getenv function. Sandboxed Twig templates should not have this access, but now do thanks to this additional environment-variable replacement behavior.

The template’s resulting value is not directly reflected in the response. To exfiltrate the value, the sandboxed Twig template cannot use network functions. But it can use a blind error-based approach similar to blind SQL injection. With enough requests, any environment variable or secret can be incrementally leaked. This can be abused to forge a session, escalate privileges with the CRAFT_SECURITY_KEY, and steal credentials for the database, SMTP server, or other connected APIs or blob storage.

Impact

An authenticated attacker, with permission to access the control panel, can render a malicious Twig template and steal arbitrary environment variables and secrets with a large number of requests, even if the Twig sandbox is enabled through enableTwigSandbox().

Duplicate Advisory

This advisory has been withdrawn because it is a duplicate of GHSA-596p-6jv8-775v. This link is maintained to preserve external references.

Original Description

Craft CMS versions >= 5.0.0-RC1 before 5.10.6 and >= 4.0.0-RC1 before 4.18.2 interpolate environment variables and secrets (via ${ENV_VAR} strings in the elementId parameter) into Twig templates before rendering, even when the Twig sandbox is enabled. An authenticated attacker with control panel access can render a malicious sandboxed Twig template and, using a blind error-based technique across many requests, incrementally leak arbitrary environment variables and secrets. These can be abused to forge sessions (via CRAFT_SECURITY_KEY), escalate privileges, and steal database, SMTP, API, or blob storage credentials. Fixed in 5.10.6 and 4.18.2.

Craft CMS versions >= 5.0.0-RC1 before 5.10.6 and >= 4.0.0-RC1 before 4.18.2 interpolate environment variables and secrets (via ${ENV_VAR} strings in the elementId parameter) into Twig templates before rendering, even when the Twig sandbox is enabled. An authenticated attacker with control panel access can render a malicious sandboxed Twig template and, using a blind error-based technique across many requests, incrementally leak arbitrary environment variables and secrets. These can be abused to forge sessions (via CRAFT_SECURITY_KEY), escalate privileges, and steal database, SMTP, API, or blob storage credentials. Fixed in 5.10.6 and 4.18.2.

Craft CMS versions >= 5.0.0-RC1 before 5.10.6 and >= 4.0.0-RC1 before 4.18.2 interpolate environment variables and secrets (via ${ENV_VAR} strings in the elementId parameter) into Twig templates before rendering, even when the Twig sandbox is enabled. An authenticated attacker with control panel access can render a malicious sandboxed Twig template and, using a blind error-based technique across many requests, incrementally leak arbitrary environment variables and secrets. These can be abused to forge sessions (via CRAFT_SECURITY_KEY), escalate privileges, and steal database, SMTP, API, or blob storage credentials. Fixed in 5.10.6 and 4.18.2.

Environment variables and secrets are interpolated into a Twig template even when the Twig sandbox is enabled, allowing them to be leaked by an authenticated attacker.

The Craft vulnerability CVE-2026-31857 was only patched by applying sandboxed Twig templating. This theoretically protects Craft CMS against RCE attacks, provided the sandbox is enabled and secure, with no known bypasses.

However, the same request parameter elementId, which allows for sandboxed Twig templates to be rendered, also includes functionality that interpolates referenced environment variables. If the parameter includes a string of the form ${ENV_VAR} then the string is replaced with the environment variable or secret from a secrets file with that name.

Afterward, the string is rendered as a Twig template. If the sandbox is disabled, Twig templates can already gain RCE or access environment variables using the getenv function. Sandboxed Twig templates should not have this access, but now do thanks to this additional environment-variable replacement behavior.

The template’s resulting value is not directly reflected in the response. To exfiltrate the value, the sandboxed Twig template cannot use network functions. But it can use a blind error-based approach similar to blind SQL injection. With enough requests, any environment variable or secret can be incrementally leaked. This can be abused to forge a session, escalate privileges with the CRAFT_SECURITY_KEY, and steal credentials for the database, SMTP server, or other connected APIs or blob storage.

Impact

An authenticated attacker, with permission to access the control panel, can render a malicious Twig template and steal arbitrary environment variables and secrets with a large number of requests, even if the Twig sandbox is enabled through enableTwigSandbox().

Duplicate Advisory

This advisory has been withdrawn because it is a duplicate of GHSA-596p-6jv8-775v. This link is maintained to preserve external references.

Original Description

Craft CMS versions >= 5.0.0-RC1 before 5.10.6 and >= 4.0.0-RC1 before 4.18.2 interpolate environment variables and secrets (via ${ENV_VAR} strings in the elementId parameter) into Twig templates before rendering, even when the Twig sandbox is enabled. An authenticated attacker with control panel access can render a malicious sandboxed Twig template and, using a blind error-based technique across many requests, incrementally leak arbitrary environment variables and secrets. These can be abused to forge sessions (via CRAFT_SECURITY_KEY), escalate privileges, and steal database, SMTP, API, or blob storage credentials. Fixed in 5.10.6 and 4.18.2.