CVE-2026-35597: Vikunja Affected by TOTP Brute-Force Due to Non-Functional Account Lockout

Vulnerability summary

CVE-2026-35597 is a high (CVSS 7.5) vulnerability in go-vikunja vikunja. EPSS estimates a 0.47% chance of exploitation in the next 30 days, higher than 39.7% of scored vulnerabilities. 1 public exploit is recorded.

Timeline

1. 10-04-2026
   PublishedVulnerability first disclosed.
2. 13-04-2026
   Last modifiedVulnerability information updated.

Description

Vikunja is an open-source self-hosted task management platform. Prior to 2.3.0, the TOTP failed-attempt lockout mechanism is non-functional due to a database transaction handling bug. When a TOTP validation fails, the login handler in pkg/routes/api/v1/login.go calls HandleFailedTOTPAuth and then unconditionally rolls back. HandleFailedTOTPAuth in pkg/user/totp.go uses an in-memory counter (key-value store) to track failed attempts. When the counter reaches 10, it calls user.SetStatus(s, StatusAccountLocked) on the same database session s. Because the login handler always rolls back after a TOTP failure, the StatusAccountLocked write is undone. The in-memory counter correctly increments past 10, so the lockout code executes on every subsequent attempt, but the database write is rolled back every time. This allows unlimited brute-force attempts against TOTP codes. This vulnerability is fixed in 2.3.0.

• CWE-307Improper Restriction of Excessive Authentication AttemptsThe product does not implement sufficient measures to prevent multiple failed authentication attempts within a short time frame.