CVE-2026-33473

Vikunja has TOTP Reuse During Validity Window

// ValidateTOTPPasscode validated totp codes of users.
func ValidateTOTPPasscode(s *xorm.Session, passcode *TOTPPasscode) (t *TOTP, err error) {
	t, err = GetTOTPForUser(s, passcode.User)
	if err != nil {
		return
	}

	if !totp.Validate(passcode.Passcode, t.Secret) {
		return nil, ErrInvalidTOTPPasscode{Passcode: passcode.Passcode}
	}

	return
}

Any user who uses 2FA could be impacted if their traffic is able to be captured, they're phished/social engineered, or other methods of attack. This disrupts one layer of the defense-in-depth model surrounding 2FA.

The application does not adequately verify the identity of a user, device, or process before granting access. Typical impact: unauthorized access to functions or data reserved for authenticated parties.

CVE-2026-33473 has a CVSS score of 5.7 (Medium). The vector is network-reachable, low privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. No fixed version is listed yet, so configuration controls and monitoring matter more in the interim.

Kodem intelligence

Store a deny-list of TOTP codes for their validity windows and check submitted codes against it to ensure none are being reused. After their validity window has closed, the 2FA code can be removed from the list.

1. What is CVE-2026-33473? CVE-2026-33473 is a medium-severity improper authentication vulnerability in code.vikunja.io/api (go), affecting versions >= 0.13, < 2.2.1. No fixed version is listed yet. The application does not adequately verify the identity of a user, device, or process before granting access.
2. How severe is CVE-2026-33473? CVE-2026-33473 has a CVSS score of 5.7 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of code.vikunja.io/api are affected by CVE-2026-33473? code.vikunja.io/api (go) versions >= 0.13, < 2.2.1 is affected.
4. Is there a fix for CVE-2026-33473? No fixed version is listed for CVE-2026-33473 yet. Monitor the advisory for updates and apply mitigations in the interim.
5. Is CVE-2026-33473 exploitable, and should I be worried? Whether CVE-2026-33473 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-33473 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-33473? No fixed version is listed yet. In the interim: Keep the dependency up to date. Ensure authentication checks are present and cannot be bypassed by manipulating request parameters.

Other vulnerabilities in code.vikunja.io/api