CVE-2026-109371

HIGH CVSS 4.0: 8.8 EPSS 0.36%
Updated Oct 15, 2026
Zitadel
Parameter Value
CVSS 8.8 (HIGH)
Affected Versions 3.0.0 — 4.18.0
Fixed In 4.18.0
Type CWE-306 (Missing Authentication for Critical Function)
Vendor Zitadel
Public PoC No

ZITADEL 3.0.0 before 4.18.0 contains a missing authentication vulnerability in the hosted Login V1 UI, where the change-username handler acts on the account bound to a login flow before any factor is verified. Unauthenticated attackers can submit a victim's login name and then post a new username to rename any active human user, including administrators, locking them out.

Attack Parameters

Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Attack Requirements
None
No additional conditions
Privileges Required
None
No privileges needed
User Interaction
None
No user interaction needed

Impact Assessment

Confidentiality
None
No data leak
Integrity
High
Complete data modification
Availability
Low
Partial disruption

CVSS Vector v4.0

Vulnerable Products 1

Configuration From (including) Up to (excluding)
Zitadel Zitadel
cpe:2.3:a:zitadel:zitadel:*:*:*:*:*:*:*:*
3.0.0 4.18.0