A stored cross‑site scripting flaw exists in the RatingButton component of Typebot’s embed package. The component renders a user‑controlled customIcon.svg field directly with Solid’s innerHTML directive, bypassing the sanitizer that protects other parts of the codebase. Because the builder preview runs on the same origin and allows unsafe inline scripts, arbitrary HTML or JavaScript can execute in the context of an authenticated builder user, enabling session hijacking and privilege escalation. This flaw is a classic example of CWE‑79.

The vulnerability affects the Typebot service provided by typebot.io. Versions 3.15.2 and all earlier releases are affected; the fix is included in version 3.16.0.

The CVSS score of 8.7 indicates high severity, and the EPSS score is not available, but the lack of listing in CISA KEV does not lower the risk for an authenticated user. An attacker who can supply or collaborate on a bot must be authenticated within the builder to exploit the flaw, after which the malicious script runs with the builder’s privileges. Because the preview bypasses the Web Worker sandbox, the attack surface is large and the potential impact spans confidentiality, integrity, and availability of the builder application.