Executive brief
Formbricks, an open-source survey platform, contains a security flaw in how it handles survey responses and PIN validation. This vulnerability allows unauthorized individuals to repeatedly test email addresses to see who has responded to a survey or to attempt to guess survey PINs using automated tools. This could lead to the exposure of participant activity or unauthorized access to protected surveys.
Technical details
A vulnerability in Formbricks 5.0.0 within `apps/web/modules/survey/link/actions.ts` stems from missing rate limits and server-side validation in the `isSurveyResponsePresentAction` and `validateSurveyPinAction` functions. An unauthenticated remote attacker can exploit this to perform email-enumeration oracle attacks, determining if specific users have responded to a survey even when the 'single response per email' feature is disabled. Additionally, the lack of rate limiting on PIN validation allows for automated brute-force attempts against protected surveys. The issue is addressed in version 5.1.0-rc.1 by implementing IP-based rate limiting (10 requests per minute) and enforcing server-side feature flag checks.
Affected products
- Formbricks Formbricks 5.0.0
Timeline
- 2026-05-21: other: Fix submitted via pull request 8094
- 2026-05-27: patched: Fix merged into main branch
- 2026-06-09: advisory: Release 5.1.0-rc.1 published
- 2026-07-06: disclosed: CVE-2026-14792 published
References
- https://github.com/formbricks/formbricks/
- https://github.com/formbricks/formbricks/commit/af6023b5ac3b030ffcea24fac799f76f3e3512c6
- https://github.com/formbricks/formbricks/pull/8094
- https://github.com/formbricks/formbricks/releases/tag/5.1.0-rc.1
- https://vuldb.com/cve/CVE-2026-14792
- https://vuldb.com/submit/850791
- https://vuldb.com/vuln/376386