CVE-2026-48147: Budibase: Unanchored Regex in `matchers.ts` Allows CSRF Bypass via Query String Injection in Budibase Worker

The buildMatcherRegex() / matches() functions in packages/backend-core/src/middleware/matchers.ts share the same structural root cause as the recently patched CVE-2026-31816: route patterns are compiled into unanchored regular expressions and tested against ctx.request.url, which includes the full query string. The CSRF middleware in the Budibase Worker uses this matching system to decide whether to skip CSRF token validation. An unauthenticated attacker can forge state-changing cross-origin requests against any Worker API endpoint by injecting a public route pattern into the query string, causing the CSRF middleware to skip token validation entirely. This allows actions such as sending admin invites, modifying global configuration, and managing users without a valid CSRF token.

CVE-2026-31816 fixed the same unanchored-regex-on-full-URL bug in server/middleware/utils.ts but left backend-core/middleware/matchers.ts untouched.