Executive brief
Vikunja is a task and project management application that provides REST APIs for authentication and account management. Versions before 2.6.0 fail to apply rate limiting to public authentication endpoints in the v2 API (login, registration, password reset), while the v1 API correctly enforces limits. This allows attackers to perform unlimited credential-guessing attacks, enumerate valid user accounts, and flood password-reset functions without throttling, potentially compromising user accounts.
Technical details
The vulnerability is a missing rate-limit enforcement (CWE-307) in the API routing layer. The registerAPIRoutesV2() function in pkg/routes/routes.go fails to apply the unauthRateLimit() middleware (a default per-IP floor of 10 requests per 60 seconds) to public authentication endpoints, instead relying on setupRateLimit() which is configuration-gated and disabled by default. This contrasts with the v1 API implementation, which unconditionally applies unauthRateLimit() to all pre-auth routes. The attack is network-reachable, requires no authentication or user interaction, and enables unbounded brute-force attacks against login, registration, and password-reset endpoints. The fix (version 2.6.0+) applies the unconditional rate-limit floor to v2 public route groups.
Affected products
- Vikunja Vikunja before 2.6.0
Timeline
- 2026-08-31: disclosed
- 2026-09-15: patched