CVE-2026-27575

Summary
The application allows users to set weak passwords (e.g., 1234, password) without enforcing minimum strength requirements. Additionally, active sessions remain valid after a user changes their password.

An attacker who compromises an account (via brute-force or credential stuffing) can maintain persistent access even after the victim resets their password.

Details

1. Weak passwords are accepted during registration and password change.
2. No minimum length or strength validation is enforced.
3. After changing the password, previously issued session tokens remain valid.
4. No forced logout occurs across active sessions.

Attack scenario:

Attacker guesses or obtains weak credentials.
Logs in and obtains active session token.
Victim changes password.
Attacker continues accessing the account using the old session.

Steps to Reproduce

1. Register using a weak password (e.g., 12345678 ).
2. Log in and Password Change functionality.
3. Change account password with single character (e.g., 1 or a )
4. Reuse the old session.
5. Observe that access is still granted.

Impact

• Persistent account takeover
• Unauthorized access to sensitive data
• Increased brute-force success probability
• Elevated risk for administrative accounts

The combination of weak password controls and improper session invalidation significantly increases both exploitability and impact.

Recommendation
Password Policy Improvements:

• Enforce strong password policies, Require passwords to be 8–16+ characters with a mix of uppercase, lowercase, numbers, and special characters.
• Block common passwords, Use a blacklist of commonly used and breached passwords.
• Use secure hashing, Store passwords using strong salted hashing algorithms like bcrypt or Argon2.
• Enable account lockout, Limit failed login attempts to reduce brute-force risk.
• Educate users, Promote strong password practices and phishing awareness.

Session Management Fix:

• Invalidate all active sessions upon password change
• Revoke refresh tokens (if applicable)
• Implement token/session versioning
• Regenerate session IDs after credential updates
• Log and notify users of password change events

Implementing both controls will significantly reduce the risk of persistent account compromise.

A fixed version is available at https://github.com/go-vikunja/vikunja/releases/tag/v2.0.0.

CVE-2026-27575 has a CVSS score of 9.1 (Critical). The vector is network-reachable, no privileges required, and no user interaction. 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

1. What is CVE-2026-27575? CVE-2026-27575 is a critical-severity security vulnerability in code.vikunja.io/api (go), affecting versions <= 0.24.6. No fixed version is listed yet.
2. How severe is CVE-2026-27575? CVE-2026-27575 has a CVSS score of 9.1 (Critical). 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-2026-27575? code.vikunja.io/api (go) versions <= 0.24.6 is affected.
4. Is there a fix for CVE-2026-27575? No fixed version is listed for CVE-2026-27575 yet. Monitor the advisory for updates and apply mitigations in the interim.
5. Is CVE-2026-27575 exploitable, and should I be worried? Whether CVE-2026-27575 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-2026-27575 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.