Please report security vulnerabilities privately via GitHub's security advisory flow:

Report a vulnerability →

Do not open a public issue or discussion for security reports.

If you can't use GitHub's flow (no account, or you'd prefer email), send a report to security@simten.dev instead. Please don't include exploit details in the first email — we'll reply with a way to share them securely.

We aim to acknowledge new reports within a few days. Once a fix is ready, we publish a coordinated security advisory to the GitHub Advisory Database so that downstream consumers of @simten/* packages are notified via Dependabot.

Reports are in scope if they affect any of:

• Published packages: @simten/core, @simten/ui, @simten/embed, @simten/mcp
• The hosted apps at simten.dev and play.simten.dev
• sandbox.simten.dev, the isolated origin that executes circuit code
• The apps/compiler, apps/verifier and apps/synth Cloudflare Container services
• Anything in this repository's CI/CD or release pipeline

Examples of issues we care about: sandbox escape from user-supplied circuit code, XSS in the embed or editor, RCE in the compiler/verifier/synth services, supply-chain risks in the release flow.

The sandbox is the boundary worth attacking. It runs untrusted circuit code on its own origin under a restrictive CSP, and takes work only over postMessage from the page that embeds it. Anything that reaches out of that origin, executes on simten.dev or play.simten.dev, or persuades the sandbox to accept instructions from somewhere other than its embedding page, is in scope.

• Self-XSS that requires a user to paste an attacker-controlled payload into their own devtools
• Reports generated by automated scanners with no demonstrated impact
• Vulnerabilities in third-party services we depend on (report those upstream)