Summary
Craft CMS: Authenticated leak of secret environment variables
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().
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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craftcms/cms to 5.10.6 or later; craftcms/cms to 4.18.2 or later
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Frequently Asked Questions
- What is GHSA-596P-6JV8-775V? GHSA-596P-6JV8-775V is a medium-severity security vulnerability in craftcms/cms (composer), affecting versions >= 5.0.0-RC1, < 5.10.6. It is fixed in 5.10.6, 4.18.2.
- Which versions of craftcms/cms are affected by GHSA-596P-6JV8-775V? craftcms/cms (composer) versions >= 5.0.0-RC1, < 5.10.6 is affected.
- Is there a fix for GHSA-596P-6JV8-775V? Yes. GHSA-596P-6JV8-775V is fixed in 5.10.6, 4.18.2. Upgrade to this version or later.
- Is GHSA-596P-6JV8-775V exploitable, and should I be worried? Whether GHSA-596P-6JV8-775V is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether GHSA-596P-6JV8-775V is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix GHSA-596P-6JV8-775V?
- Upgrade
craftcms/cmsto 5.10.6 or later - Upgrade
craftcms/cmsto 4.18.2 or later
- Upgrade