Budibase: SSRF via OAuth2 token endpoint URL reaches internal hosts and cloud metadata

Budibase is an open-source low-code platform. Prior to 3.39.0, fetchToken in the OAuth2 SDK makes a POST to a builder-supplied URL with plain node-fetch, skipping the blacklist.isBlacklisted check that every other outbound fetch path in the codebase uses. The Joi schema for the OAuth2 URL has no scheme or host restriction. This vulnerability is fixed in 3.39.0.