A JSON value supplied as a base64-encoded "state" parameter to the Google Sheets OAuth callback is decoded without cryptographic integrity protection or any authorization checks. The embedded workspaceId, typebotId, blockId, and redirectUrl are accepted at face value. This flaw allows an authenticated user who can obtain a valid Google OAuth code to modify the state value and create Google Sheets credentials in any workspace where that user has exponential access, as well as attach those credentials to arbitrary blocks within any Typebot whose identifiers are known. The impact is the unauthorized creation of credentials and the ability to modify the configuration of any uninhibited Typebot, potentially exposing sensitive data or compromising downstream integrations.

The vulnerability affects all deployments of baptisteArno:typebot.io Typebot versions prior to 3.17.0. Versions 3.17.0 and later include a patch that validates the authenticated user's write permissions before creating credentials or updating Typebot groups.

The vulnerability carries a CVSS score of 7.1, indicating a moderate severity with potential for impact if exploited. However, its EPSS score of less than 1% suggests that the likelihood of exploitation is currently very low, and it is not listed in the CISA KEV catalog. The attack vector requires an authenticated user with a valid Google OAuth code and knowledge of target workspace and Typebot identifiers, which limits the practical exploitability to users who have already authorized the application or have been socially engineered into providing the OAuth code. Once these conditions are met, the attacker could add credentials to an unauthorized workspace and modify arbitrary Typebot configurations.